i've run the shimano freewheels before, a few actually, and i've only once had much trouble getting them off...
i put a big fat flathead screwdriver (the thicker the tip the better) against the notch and tap it with a hammer counter clockwise. it's worked fine for me on 3 freewheels, the only time i had trouble was some old bmx wheel that i had no history on, but the piece of the freewheel with the notches just deformed from the screwdriver.
that said, if you're gonna go the destruction route like on the parktools website, might as well try that first...