If you are still considered a studend, you are entitled to a student's work permit and there is no need to do it through your partnership. However, if you are no longer a student, then you would want to apply for the Cohabitation Visa (via the commune)! Once you have that visa you can then start applying for your work permit (type C) at the Work Visa Office. This is a long long process, it took me 6 months to do it!
Let me just warn you, you will need a LOT of patience and you should document and take copies of everything! If they will let you.. get the names of people that you deal with, the time, date and if you are really lucky..get them to sign it! This is to save you some problems down the road..you'll need it!
Check out this thread, for a darn good outline of what is needed for Cohabitation.
http://forum.expatica.com/Cohab-Visa-Marriage-t105379.htmlHere is also a good site to start going through for Cohabitaion!
http://www.diplomatie.be/en/travel/visa/vi...sp?TEXTID=44225Good luck! You'll need it. OH! If you can, try to deal with the smaller communes! You will have less of a wait.