Just decided to reply to the OP here as I now have 1st hand experience. In case somebody Googles and comes across this. There appears to be three main pieces to the PII packaging, a plastic backing, a metal front (heat spreader for direct cpu contact), and a thin-ish plastic piece underneath the metal heat spreader.
1. the thin plastic piece underneath the heat spreader must come off first. There are two spots on the plastic, up against the heat spreader (hereafter : "spreader") that appear made to put a straight screwdriver, turning it to pull the plastic away from the spreader. Do so. If you applied NINJA FORCE! the plastic came off and you see the long arrow-ish thingies that went up into the housing to hold it on and you're wondering what they scraped, pulled, and snapped off trying to keep the plastic piece on. NOT to worry, if you used your NINJA SENSE! while removing, you were able to keep breakage to a minimum.
2. Read "the art of war"
3. Now put the straight screwdriver into the seam where the spreader touches plastic on the metal sides (where there may or may not be little handle thingies that are used to keep the CPU/housing in place when in the SLOT). Time for more NINJA FORCE! You will probably see that the little handle thingies come out and are part of the mechanism keeping the housing together.
4. There should be a total of 6 studs that are pressed in to the metal spreader. These go through the PCB and into the plastic backing. You are now at the most sensitive point. Meditate....NINJA SENSE! must be at least 10. You need to seperate the plastic backing from the spreader. Grasp the spreader and bend the plastic away from it, TRY not to bend the spreader. The PCB will rest on the pressed in studs, so should be OK. Once the plastic portion of the housing is pulled away, you have only to pick off any black plastic left on the studs then remove the PCB
Remember! If you break the PCB, My Kung-Fu is BETTER!