samba - Oct 2004 - Full Name from User Manager to /etc/passwd

Hi all, 

I use samba 3 with WindowsXP clients. I'd like to add a new user with 
User Manager (usrmgr.exe) from the client, but how can I solve, that 
this procedure takes the Full Name (what I set in usrmgr) to the 
linux /etc/passwd file. (the linux can store a full name in /etc/passwd, 
but how can the usrmgr take it to /etc/passwd automatically)
I tried to search, what should I write to the "add user script" line
to do
this, but I couldn't find.

Thanks for your answers:
  Gergo