I have a small update here.
Today, I successfully tested the login part with J and I guess I can say that its like 99% finished. (the login part that is).
That basically means, if you know the url, you could login to eh.. nothing (you just can login) with your forum username and password, and I can actually use that to do stuff like: linking a level to you etc.
I think this actually was one of the hardest parts of the system, so things will be easier from now on.