Hide/Unhide Selected Courses for Registration

I need a way to hide and unhide course instances for registration. We want students to be able to self-register for almost everything. We have intraterm modules embedded within the larger term. Students are permitted to register for these modules much later than the beginning of the term (way past drop-add / open registration), but I have to do it for them in Populi. I do not want to create a non-standard term for every module. Is it possible to create a method by which I might globally hide all course instances from registration view (with the click of a single button), then selectively unhide a few (modules) so that students can see them? Thanks, Mark