Autologin Xenith with mac.ini

Hello

I would like to use mac.ini files which includes a username and a password
to log on automatically. The goal should be, that the user don't have
to type in any credentials. I have now the problem, that i cannot set the
username. I tried with the parameter "username=" but it doesn't work. The
parameter "password=" works fine. For my Thin-OS Clients it works, but with
my Xenith's not. The message "Invalid Statement: USERNAME" appears in the
event log.

Is there a parameter which I can use to set the username in a mac.ini file?
Or is this only possible for thin-os clients?

Thanks a lot for any inputs.

Zuegi