これはあなたが望むことをします。上記の選択コントロールのタイプで見つけたWebサイトでテストしました：

>>> import twill.commands
>>> import BeautifulSoup
>>> import re
>>> 
>>> a=twill.commands
>>> a.config("readonly_controls_writeable", 1)
>>> b = a.get_browser()
>>> b.set_agent_string("Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.8.1.14) Gecko/20080404 Firefox/2.0.0.14")
>>> b.clear_cookies()
>>> url="http://www.thesitewizard.com/archive/navigation.shtml"
>>> b.go(url)
==> at http://www.thesitewizard.com/archive/navigation.shtml
>>> form=b.get_form("1")
>>> b.showforms()

Form #1
## ## __Name__________________ __Type___ __ID________ __Value__________________
1     newurl                   select    dummymenu    [''] of ['', '#', '#', '', '#'] 


Form #2
## ## __Name__________________ __Type___ __ID________ __Value__________________
1     cmd                      hidden    (None)       _s-xclick 
2  1  submit                   image     (None)        
3     encrypted                hidden    (None)       -----BEGIN     PKCS7-----MIIHwQYJKoZIhvc ... 


Form #3
## ## __Name__________________ __Type___ __ID________ __Value__________________
1     None                     textarea  pagelinkcode <a href="http://www.thesitewizard.co ... 


Form #4
## ## __Name__________________ __Type___ __ID________ __Value__________________
1     q                        text      searchterms   
2  1  None                     submit    (None)       Search 


Form #5
## ## __Name__________________ __Type___ __ID________ __Value__________________
1     cmd                      hidden    (None)       _s-xclick 
2  1  submit                   image     (None)        
3     encrypted                hidden    (None)       -----BEGIN PKCS7-----MIIHwQYJKoZIhvc ... 

>>> valOpts=[]
>>> for c in form.controls:
...     if c.name=="newurl":
...        if 'items' in c.__dict__:
...           print "control %s has items field length %s" % (c, len(c.items))
...           if len(c.items)>0:
...              for itm in range(len(c.items)):
...                 valOpts.append(c.items[itm].attrs['value'])
... 
control <SelectControl(newurl=[*, #, #, (), #])> has items field length 5
>>> print valOpts
['', '#', '#', '', '#']
>>>

フォームをデバッグするときは、次を使用します。

def getFormControlByLabel(self, form, label):
  for control in form.controls:
     self.log.debug("checking control %s dict = %s" % (control,control.__dict__))
     if 'items' in control.__dict__:
        self.log.debug("control %s has items field len %d" % (control, len(control.__dict__['items'])))
        if len(control.items) > 0:
           if 'label' in control.items[0].attrs:
              self.log.debug("control %s has label %s" % (control, control.items[0].attrs['label']))
              if control.items[0].attrs['label'] == label:
                 self.log.debug("control %s has label %s" % (control,label))
                 return control
  for control in form.controls:
     try:
        if control.items[0].attrs['label'] == label:
           # y.items[0].attrs['label']
           self.log.debug("control %s has matching label %s" % (control,label))
           return control
        else:
           self.log.debug("control %s has label %s" % (control,control.items[0].attrs['label'] ))
     except:
        pass