I've taken my pulley off so many times I can't remember exactly how I torque it to 100 lbs or more. I either jammed a screwdriver in the cam sproket to prevent the engine from turning over or put an adjustable wrench on the cam (not the lobes, my aftermarket cam has places to put a wrench). I don't think the cam idea was the best because all that torque would be against the aluminum head. Come to think of it, I think I did use a screwdriver in the sproket, a piece of wood under the rear tires, and someone in the car holding down the brake. I admit, its not easy, but if I remember the torque is applied in stages it seems, as the crank bolt will tighten then turn the enigne, tighten more, turn the engine more....
Be careful to get the pulley exacly lined up with the locator pin on the crankshaft too. If its off or if you damage the pulley taking it off, the pulley can break. The first time I did this I thought my front seal was leaking. Turns out the pulley was cracked around the part that slips on the crank. UGH!!! That's happened to me about three times. So, just be careful. Unexpected trips to the junkyard at 4:30 in the afternoon are not fun!!
Chris