The easiest way I found to do it requires a CD-ROM mounting screw.
Place the screw so the head is on the bottom (so the long skinny threads are going up). Position the mounting holes on the hologram side of the CPU above the screw. Push down, so the screw goes into the mounting hole, and it'll pop the mounting pin out.
You might have to use a screwdriver to get the screw out, but that's the way I got my Intel heatsink off my P3 700.