yeah bro sheetrock is key..i had the same exact situation with renting, and i needed to cut 2 holes. anyhow, i DO have attic access, and i also have sheetrock. Just drew a circle with a 6 inch coffee can lid, and cut the holes right out with a simple utility knife. quick clean and easy. Also have the ceiling holes to just put back up before i move, putty, and sand it. will look good as new. if you indeed do have wood, a saw would be key. However your lucky its in a closet, for no one will notice if you just save the holes you cut out and simply wood glue them back. no one looks at closet ceilings that close. your def gonna have to do something soon, cuz its gonna get hot my man.