Shamelessly replying to myself here to bump to the top in the hopes of getting a response 
Does anyone know how a student can be prevented from enrolling in a course? I don't mean all coures, just certain courses and I need something a bit more 'advanced' / automated than the enrollment key.
Is there a way to create special roles (level specific in our case) that then are only allowed to enroll in certain courses?
Jason
P.S. How about a hack to the Availability portion of course settings to include "This course available to ********" with ****** being a preset role?