更新:
このプロセスについてさらに多くのことを学び、私の答えが完全にはほど遠いことに気付いたので、私は自分の答えを完全に書き直しています。
最初に、アイデンティティの IdentyXXX クラスから継承して、エンティティを作成しました (ここではサンプル用に 1 つだけ提供します)。
using System;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Security.Claims;
using System.Threading.Tasks;
using Microsoft.AspNet.Identity;
using Microsoft.AspNet.Identity.EntityFramework;
using NTier.Web.Core.Interfaces.Common;
using NTier.Web.Core.Interfaces.DataModels;
using NTier.Web.Core.Interfaces.Stores;
namespace NTier.Web.DataAccess.Entities
{
    public sealed class MemberEntity : IdentityUser<Guid, MemberLogin, MemberRole, MemberClaim>,
        IMemberDataModel, IAuditable
    {
        public MemberEntity()
        {
            Id = Guid.NewGuid();
        }
        #region Overrides of IdentityUser<Guid,MemberLogin,MemberRole,MemberClaim>
        public override Guid Id
        {
            get { return base.Id; }
            set
            {
                base.Id = value != Guid.Empty ? value : base.Id;
            }
        }
        #region Overrides of IdentityUser<Guid,MemberLogin,MemberRole,MemberClaim>
        public override string PasswordHash
        {
            get { return base.PasswordHash; }
            set
            {
                base.PasswordHash = !string.IsNullOrWhiteSpace(value) ? value : base.PasswordHash ;
            }
        }
        #endregion
        #endregion
        public Guid Identity
        {
            get { return Id; }
            set
            {
                if (value != Guid.Empty)
                {
                    Id = value;
                }
            }
        }
        public string Moniker { get; set; }
        [MaxLength(256)]
        public string FirstName { get; set; }
        [MaxLength(256)]
        public string LastName { get; set; }
        [MaxLength(256)]
        public string Middle { get; set; }
        public async Task<ClaimsIdentity> GenerateUserIdentityAsync(UserManager<MemberEntity, Guid> manager)
        {
            // Note the authenticationType must match the one defined in CookieAuthenticationOptions.AuthenticationType
            var userIdentity = await manager.CreateIdentityAsync(this, DefaultAuthenticationTypes.ApplicationCookie);
            // Add custom user claims here
            return userIdentity;
        }
        #region Implementation of IAuditable
        public DateTime DateTimeCreated { get; set; }
        public DateTime? DateTimeModified { get; set; }
        public DateTime? DateTimeDeleted { get; set; }
        public DateTime? DateTimeArchived { get; set; }
        public string CreatedBy { get; set; }
        public string ModifiedBy { get; set; }
        public string DeletedBy { get; set; }
        public string ArchivedBy { get; set; }
        public bool IsDeleted { get; set; }
        public bool IsArchived { get; set; }
        #endregion
    }
}
次に、DbContext の OnModelCreating メソッドを次のようにオーバーライドしました。
protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            if (modelBuilder == null) throw new ArgumentNullException("modelBuilder");
            modelBuilder.Entity<WebSiteEntity>()
                        .HasKey(site => site.Identity)
                        .ToTable("WebSite");
            #region Security
            modelBuilder.Entity<MemberEntity>()
                        .ToTable("Member")
                        .HasMany(u => u.Roles)
                        .WithRequired()
                        .HasForeignKey(ur => ur.UserId);
            modelBuilder.Entity<MemberEntity>()
                        .HasMany(u => u.Claims)
                        .WithRequired()
                        .HasForeignKey(uc => uc.UserId);
            modelBuilder.Entity<MemberEntity>()
                        .HasMany(u => u.Logins)
                        .WithRequired()
                        .HasForeignKey(ul => ul.UserId);
            modelBuilder.Entity<MemberEntity>()
                        .Property(u => u.Moniker)
                        .HasMaxLength(50)
                        .HasColumnAnnotation("Index",
                                            new IndexAnnotation(new IndexAttribute("UserNameIndex")
                                                                {
                                                                    IsUnique = true,
                                                                    IsClustered = false,
                                                                    Order = 2
                                                                }))
                        .HasColumnAnnotation("Index",
                                            new IndexAnnotation(new IndexAttribute("MonikerIndex")
                                                                {
                                                                    IsUnique = true,
                                                                    IsClustered = false,
                                                                    Order = 1
                                                                }));
            modelBuilder.Entity<MemberEntity>()
                        .Property(u => u.LastName)
                        .HasMaxLength(256)
                        .HasColumnAnnotation("Index",
                                            new IndexAnnotation(new IndexAttribute("UserNameIndex")
                                                                {
                                                                    IsUnique = true,
                                                                    IsClustered = false,
                                                                    Order = 3
                                                                }))
                        .HasColumnAnnotation("Index",
                                            new IndexAnnotation(new IndexAttribute("MonikerIndex")
                                                                {
                                                                    IsUnique = true,
                                                                    IsClustered = false,
                                                                    Order = 2
                                                                }));
            ;
            modelBuilder.Entity<MemberEntity>()
                        .Property(u => u.FirstName)
                        .HasMaxLength(256)
                        .HasColumnAnnotation("Index",
                                            new IndexAnnotation(new IndexAttribute("UserNameIndex")
                                                                {
                                                                    IsUnique = true,
                                                                    IsClustered = false,
                                                                    Order = 4
                                                                }))
                        .HasColumnAnnotation("Index",
                                            new IndexAnnotation(new IndexAttribute("MonikerIndex")
                                                                {
                                                                    IsUnique = true,
                                                                    IsClustered = false,
                                                                    Order = 3
                                                                }));
            ;
            modelBuilder.Entity<MemberEntity>()
                        .Property(u => u.Middle)
                        .HasMaxLength(256);
            modelBuilder.Entity<MemberEntity>()
                        .Property(u => u.UserName)
                        .IsRequired()
                        .HasMaxLength(256)
                        .HasColumnAnnotation("Index",
                                            new IndexAnnotation(new IndexAttribute("UserNameIndex")
                                                                {
                                                                    IsUnique = true,
                                                                    IsClustered = false,
                                                                    Order = 1
                                                                }))
                        .HasColumnAnnotation("Index",
                                            new IndexAnnotation(new IndexAttribute("MonikerIndex")
                                                                {
                                                                    IsUnique = true,
                                                                    IsClustered = false,
                                                                    Order = 4
                                                                }));
            modelBuilder.Entity<MemberEntity>()
                        .Property(u => u.Email)
                        .HasMaxLength(256);
            modelBuilder.Entity<MemberRole>()
                        .HasKey(userRole => new
                                            {
                                                userRole.UserId,
                                                userRole.RoleId
                                            })
                        .ToTable("MemberRole");
            modelBuilder.Entity<MemberLogin>()
                        .HasKey(login => new
                                        {
                                            login.UserId,
                                            login.ProviderKey,
                                            login.LoginProvider
                                        })
                        .ToTable("MemberLogin");
            modelBuilder.Entity<MemberClaim>()
                        .ToTable("MemberClaim");
            modelBuilder.Entity<RoleEntity>()
                        .ToTable("Role");
            modelBuilder.Entity<RoleEntity>()
                        .Property(r => r.Name)
                        .IsRequired()
                        .HasMaxLength(256)
                        .HasColumnAnnotation("Index",
                                            new IndexAnnotation(new IndexAttribute("RoleNameIndex")
                                                                {
                                                                    IsUnique = true
                                                                }));
            modelBuilder.Entity<RoleEntity>()
                        .HasMany(r => r.Users)
                        .WithRequired()
                        .HasForeignKey(ur => ur.RoleId);
            #endregion