Most sockets have little plastic tabs which are meant for a metal clip which holds the heat sink on. Take a broad flat headed screwdriver and use the plastic tabs to pry against and edge each corner up a little at a time. The whole CPU will eventually start coming up after half a dozen rotations or so.
Are you going to up the speed to 33 MHz?
http://homepage.mac.com/schrier/q605.html
You can go up to 40 MHz if you can find a 20 MHz oscillator.