I improvised Sheldon's fixed cup removal tool with a 1/2 inch bolt, nut. lock washer, and a couple flat washers. Put the bolt and a flat washer through the inside of the bottom bracket, then add a flat washer and a lock washer, then the nut on the outside. When you tighten the nut, it grabs the cup and spins it correctly to back out the left hand threads. You are relying on friction, so make sure all the bearings and grease are cleaned out first.