user and group id mappings

I'm a bit confused about user and group mappings in sfs.  It looks
like I need to edit or cause to be modified the /etc/sfs/sfs_users
file, but it's not entirely clear from the manual / man pages whether
I should edit this myself or use some program to administer them.  Nor
precisely how to do these things.  Probably this would be clear if I
were a sysadmin instead of a programmer and grad student...

The issue is that user 512/512 on the server, member on the server of
groups 5551 and 5552, is known on the client as 1000/1000 and should
be members of those groups.

So the mappings are

    server	client
    uid 512	uid 1000
    gid 512	gid 1000
    gid 5551	gid 1003
    gid 5552	gid 1002

Currently only the first two of these work correctly, and even there
it's only access permissions that work, ls -lg still shows numbers
instead of names.

Thanks in advance for any help / pointers.

-- 
 Jeff

 Jeff Abrahamson  <http://www.purple.com/jeff/>    +1 215/837-2287
 GPG fingerprint: 1A1A BA95 D082 A558 A276  63C6 16BF 8C4C 0D1D AE4B

 A cool book of games, highly worth checking out:
 http://www.amazon.com/exec/obidos/ASIN/1931686963/purple-20