Some information is 'hidden' in the DSL-FAQ of the driver CD! You should have a look at that help file.

Create a new connection and set it to this:

Login window:
The login name is <????><????>#<Mitbenutzernummer(0001)>@t-online.de and the password is <????>

Any questions? Corrections? Problems? Mail me, I may have a useless idea...