If I recall, you must be a domain user to set ACL's on a CIFS share so any local account probably won't work.
Why not get a hold of something like setacl: http://setacl.sourceforge.net/
After a little more playing, it looks like I can connect with CIFS to the share using our filer's local "administrator" account and can set ACLs to my heart's content.
Steve Losen scl@virginia.edu phone: 434-924-0640
University of Virginia ITC Unix Support