Vbulletin user database only?

Hi,

I've searched, and apologize if I've missed it, but can someone point me to the steps needed to have Gallery share a VB user database?

Only thing I'm looking to do is be able to give my VB users a gallery account without them (or me) having to do it for them, and one which shares the same user name and login as their VB member info.

Thanks!