I am trying to accomplish the same mission here and have been totally unsuccessful.
I'd be willing to pay for someone to do this for my web site, as well as setting up my php-nuke to utilize the logins from vbulletin.
I give up trying it myself. Please do not recommend vbportal either. It just does not fulfill my complete needs. I do not want to post stories in my message board, which, unless I am mistaken, that is what vbportal does.
Any takers? I don't have a lot of cash, but I am willing to listen to offers.
bob@azprosports.com