You can do it as I have created a custom field and I force users to fill it in, then it shows in the postbit but I can't remember how I did it but I know it was not hard. I will try and find out how I did it.
--------------- Added [DATE]1289319022[/DATE] at [TIME]1289319022[/TIME] ---------------
Ok found it
It is set in User Profile Fields/User Profile Manager.
Thank you but this is not that i want.
I have already created customfields.
But some users are not fill it. How can i force them to fill it.