Subfolder won't permenantly redirect to subdomain
I have a forum installed in a subdirectory (http://www.example.com/forums/), but I want to have it accessed through forums.example.com and all traffic from the subdirectory passed to the subdomain.
From what I can read online this is a little bit harder since the subdirectory and subdomain would be the same name. I'm on a shared server so I can't setup the subdomain outside the root folder and ideally I want to still have it setup so other scripts I use outside of the forums can access the /forums/ subfolder (i.e. DOCUMENT_ROOT using PHP).
I'm not well versed at all in this so any help would be appreciated.