It can also be helpful to secure assistance from a friend. Have them back you up on the BB on the non-drive side as you push and turn. I like to do it with both tires on the ground rather than relying on my bike stand. That also helps stabalize things. Or, lay the bike down on a piece of carpet or other soft surface, non drive side down. Most times when I have a problem with the tool wanting to jump out is because of poor back-up. The idea of a woodworking clamp is also a good one. They sell them with rubber pads. The important side to be firmly torqued is the drive side on cartridge style BBs.