Okay, I am making a script for my site. However, I want it so that in order to upload you need to have an account on the forums, and prefered be part of a certain group. Is there anyway that can be done? If so, how hard are we looking at.

IPB's ACLs already do this ( + IP.Downloads, or just set up a forum section)
Or, iirc, phpbb has acls that do this too.

Use a DB, or go the EABG approach - use .htpasswd .

Why wouldn't it be able to? Just find out the DB username/password for the DB the forums use and then connect and check for the username. Doesn't seem too complicated, especially if you already have the upload script.