That's way too humane. This is what razor blades are for. Start at the feet and work your way up. See how many individual cuts you can make per square inch. Don't go too deep, you don't want it too bleed out. Pour vinegar on it as you go. Make sure you have some epinephrine shots and defibrillator paddles in case it crashes due to shock. Properly done it should take days.  Or alternatively just tie it to tree and put a motorcycle tire around it's head, douse the tire  in gasoline (make sure not to get any on the ham) and then light a match. That's an old classic.