Or, since you don't *have* a Dremel, you can do the same with a regular power drill. The trick is, once the screw head is badly thrashed, trying to get the drill to start centered on the screw head. If you have a drill press, you might be able to purchase a Dremel burr bit and chuck that in the drill press, then use it to "mill" off the screw heads. Might work, might not, but be very careful in doing this sort of thing with a drill press; significant side forces can unseat the chuck from the spindle, which gets exciting if you have it spinning at the higher speeds (say, 1500 rpm) at the time...