macosxhints – December 10, 2003.   You can specify Workgroup (along with user ID) in the SMB connect-to string. For example:
smb://WORKGROUP;machine.somewhere.com/Share
smb://WORKGROUP;User@machine.somewhere.com/Share
smb://WORKGROUP;User:Password@machine.somewhere.com/Share/
Unrelated hint to clear DNS cache: lookupd -flushcache (might need sudo)
