Synchronize site login with vBulletin login

[denewey]

I have developed a site in php with it's own login. I would like to set it up so that there is only one log in to access the site and the vBulletin forum. I already posted at vBulletin.com and was told:

"Integrating vBulletin with a non-vB member system would require a rather extensive modification of the code. Of course, we cannot provide official support for code modifications. What most people do is modify their current system to use the vB member system."

Is there anyone who has done this and can you give me an idea of what it would take to get this set up?

thank you.