Accessing user/cookie info outside of vBulletin

[Greg-J]

I'm creating a pseudo-marketplace outside of vbulletin and I'm running into a snag where I think many people do and I can't seem to find the solution I'm after.

I really need to be able to know if a user is logged into vbulletin and if they are, get their messages information, (userid, # of new/old messages etc.) and other things like the popup notification when they get a new message (although that's trivial at this point).

Any help would be much appreciated. I'm really just looking to know what vbulletin files/functions/classes I need to be using/including and any tips you might have the subject.