This does what you want. Tested on a website I found with the type of select control you have above:
>>> 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
['', '#', '#', '', '#']
>>>
