Schlock is not an event which generally just works (TM) without causing too much trouble to the organizers. Organizing schlock is considered the responsibility of the president. Sorry. I've run schlock twice and run into difficulties both times, so i'll outline the potential problems here, rather than providing a working game plan, since i don't know one.
The way schlock movies are frequently decided is by choosing a few spring-semester meetings at which to pass around catalogs from movie companies. Swilfolk look through the catalogs and read the descriptions for things that look promising. The presidents write down things which receive some approval, and eventually a vote is taken.
Another way to pick movies is to place the catalogs somewhere accessible (like George) and tell people to go up there and look through them and write down suggestions. This doesn't actually work, since no one will do it. There's not a really good alternative to passing catalogs at meeting, even though it is distracting. There will be a few fairly slow meetings spring semester. Try one of those.
One piece of advice: choosing movies by catalog-flipping is a far from foolproof method of getting movies that are bad enough to be interesting. Many bad movies are simply boring, and even a really promising sounding title and description can belong to a very disappointing movie. To give a real-life example: in spring 1998, we showed ``The Incredible Creatures Who Stopped Living and Became Mixed-up Zombies (the musical)''. There is currently a copy of this movie in George. Don't watch it. Even MST3K didn't have anything interesting to say about this one.
The most helpful asset during schlock-choosing is an obscure movie enthusiast. Any movie chosen for schlock should have a recommendation from at least one person who has seen it, or at least heard of it. If you don't have a local movie enthusiast, write to the chit-chat list or some such and try to find a knowledgeable dinosaur.
The optimal mix for schlock is one sci-fi, one fantasy, and one horror. Horror is much easier to find than the other two, so do what you can. Also, 3-d movies are popular and get pretty good turnout (and we own a tube of 3-d glasses), though the movies themselves are often disappointing. We don't show ``Plan 9 from Outer Space'' as a schlock movie.