Which class or file handles updating a users cookie

[wce]

Hey there,

I've had a site up for about a year now, and I want to add a vbulletin forum to it... but I want it so that when a user logs into the forums, and goes back to the content (non-vb pages), their cookie stays active (is updated or whatever) so that if they go back to the forums they're still logged in.

I've tried including global.php, which works to read the cookie data, but it does not appear to be updating the cookie data causing the users cookie to expire while they're looking at content pages, and when they go back to the forums they're no longer logged in.

What file would I need to include in my non-vb pages, or what class would I need to work with in order to manually update a users cookie to keep them still logged into the forum even while they're browsing my content pages?

I've tried searching everywhere, any recommendations would be greatly appreciated.

Thanks