[Samba] How to rename a user in Samba 3?

[Mi]

Hello,

Is there an easy (scriptable) way of renaming users on a Samba 3 PDC?

I need to change the login and real name, but want to keep the (roaming) 
Windows profile as it is.

usermod lets me change the Unix side of things, but it doesn't look like 
I can use pdbedit or something else to change the Samba side.

With older Samba versions, I could have edited smbpasswd, but now it 
seems everything is in /var/lib/samba/passdb.tdb.


I'm using Samba "Version 3.0.14a-Debian" and I have

  passdb backend = tdbsam, guest

in smb.conf.

How do you proceed if you want to rename a user?

Thanks for any help,

Mi