That's just a compound, like the stuff you'd put between a CPU and its heatsink. Look for the thermal epoxy or adhesive, Arctic Silver makes it and Fry's should sell it (that's where mine came from anyways).
You may need to use more force to break the thermal epoxy bond.
Do you have a link? I want to make sure I get the right stuff!
Force it, like how much? I dont want to break the stuff LOL