Mine screws in also. A lock is a good idea; however, I am not sure if it would work because I do not think there is anything that holds the bottom of the monitor access panel in place. Most cabinet back doors that lift out have a tongue and groove joint at the bottom of the door and a lock on top so it will not slip out of place. I think the access panel just rests on the monitor shelf and would slide out if you just put a lock at the top.