I have my Nokia 6600 working as a modem using Fedora 4. I have tried unsuccessfully to use the same instructions to get it working on Suse 10 and alson on Ubuntu. I am a newbie and relying on the patience of various friends. If you are still needing specific instructions how to use the bluetooth nokia6600 modem I can send you hat I have been given, which I think is based on the advice you were sent from that German chap.
I also would like to know how you progress with the synchronization software as I have been unable to do it so far. I am completely fed up with windows and refuse to return to the XP compatible Nokia software.
Good luck and let me know if you need those instructions