ok after 3 hours i finally found a way to get facebook compatibility with Jabberwocky/KwaKwa.

1. create an account on jabber.org.by
2. Start Jabberwocky and login.
3. Then go to roster and register for facebook transport. right after that all your accounts will be loaded into the userlist. Problem here: it will only show the UserID of facebook without any name or other references.
4. then start KwaKwa and enter jabber server/username + password into prefs
5. The same userlist will appear, but now you can right click on every user and select "edit contact". Now you can do "Fetch from Network". The corresponding username + profile picture will be loaded.

I dont know if its possible to register facebook transport on the jabber server with KwaKwa, so maybe jabberwocky is completely unneccesary.