Integrating vB with my own CMS

[UnrealAnt]

I'm sure this is a question which has been asked a million times, so hopefully there'll be a fairly simple answer.

I'm in the process or programming my own Content Management system however I'd like to integrate it with vBulletin (since it seems pointless for my visitors to have to register to use certain features on the site, and then register again to use the forums). Obviously this means that I need to write a wrapper for many of the vBulletin functions, as well as try to reproduce sessions.php such that it works on the CMS.

However I'm not really sure where to start with this. Has anyone any experience with this kind of thing? To make it even more troublesome, I'm trying to integrate with vB3. I appreciate that hacking vB3 is currently not supported over here at vBorg so even if you can only give advice which related to vB2, I should be able to apply it to vB3

Thanks all,

Ant