samba - Apr 2004 - Possible to add domain user accounts to a local linux group on samba-3 domain member server?

Hello,
  I've set up a Samba 3.0.2a domain member server on an existing Windows 
NT4 domain utilizing Winbind to resolve user authentication to my server. 
I would like to create local groups on my Samba server containing users 
from the NT domain to control access to shares on the Samba server.  I've 
googled for a couple days trying to find something that will help me do 
this, but the suggestions I've found (use gpasswd to add domain users to a 
local group) have failed (error saying user not found).  Has any progress 
been made towards this end, or is it planned for any future release?  I am 
unable to create groups on the domain to facilitate access control that 
way.  Is Winbind limited to only using domain groups, or is the limitation 
within the Linux OS itself to understand the domain user concept?  Any 
insight you can provide would be greatly appreciated.

Thank,

Jason McGlamary
PC/LAN Specialist
Division of Nursing - Nursing Informatics
Co-Chair WHC/NRH/IS Focus Forum
Washington Hospital Center