Ok, here's my story:
I run a well established "Resident Evil" fansite, PR4, many backlinks and good traffic. However, when i installed vBulletin a year ago i put it on a seperate server, because one was too less for both the site and forums.

Therefore, my forums have exactly one backlink, and thats from the mainsite. I want to SEO the forums now and installed vbSEO, the question now is how to get quality backlinks for my forums and not the mainsite only..

Guess, there's no other alternative but submitting to directories right? No site which offers related/similar content would affiliate with my forums if they're already affiliated with the mainsite and many of them are.