インターネットのどこかで見つけたこのコードを使用しています(おそらくStackOverflowでも。正確には覚えていません)
Function ChooseFile (ByVal initialDir, filter)
dim shel, fso, tempdir, tempfile, powershellfile, powershellOutputFile,psScript, textFile
Set shell = CreateObject("WScript.Shell")
Set fso = CreateObject("Scripting.FileSystemObject")
tempDir = shell.ExpandEnvironmentStrings("%TEMP%")
tempFile = tempDir & "\" & fso.GetTempName
' temporary powershell script file to be invoked
powershellFile = tempFile & ".ps1"
' temporary file to store standard output from command
powershellOutputFile = tempFile & ".txt"
'if the filter is empty we use all files
if len(filter) = 0 then
filter = "All Files (*.*)|*.*"
end if
'input script
psScript = psScript & "[System.Reflection.Assembly]::LoadWithPartialName(""System.windows.forms"") | Out-Null" & vbCRLF
psScript = psScript & "$dlg = New-Object System.Windows.Forms.OpenFileDialog" & vbCRLF
psScript = psScript & "$dlg.initialDirectory = """ &initialDir & """" & vbCRLF
'psScript = psScript & "$dlg.filter = ""ZIP files|*.zip|Text Documents|*.txt|Shell Scripts|*.*sh|All Files|*.*""" & vbCRLF
psScript = psScript & "$dlg.filter = """ & filter & """" & vbCRLF
' filter index 4 would show all files by default
' filter index 1 would should zip files by default
psScript = psScript & "$dlg.FilterIndex = 1" & vbCRLF
psScript = psScript & "$dlg.Title = ""Select a file""" & vbCRLF
psScript = psScript & "$dlg.ShowHelp = $True" & vbCRLF
psScript = psScript & "$dlg.ShowDialog() | Out-Null" & vbCRLF
psScript = psScript & "Set-Content """ &powershellOutputFile & """ $dlg.FileName" & vbCRLF
'MsgBox psScript
Set textFile = fso.CreateTextFile(powershellFile, True)
textFile.WriteLine(psScript)
textFile.Close
Set textFile = Nothing
' objShell.Run (strCommand, [intWindowStyle], [bWaitOnReturn])
' 0 Hide the window and activate another window.
' bWaitOnReturn set to TRUE - indicating script should wait for the program
' to finish executing before continuing to the next statement
Dim appCmd
appCmd = "powershell -ExecutionPolicy unrestricted &'" & powershellFile & "'"
'MsgBox appCmd
shell.Run appCmd, 0, TRUE
' open file for reading, do not create if missing, using system default format
Set textFile = fso.OpenTextFile(powershellOutputFile, 1, 0, -2)
ChooseFile = textFile.ReadLine
textFile.Close
Set textFile = Nothing
fso.DeleteFile(powershellFile)
fso.DeleteFile(powershellOutputFile)
End Function