Mike, FWIW, I had a cotter pin like that -- reason it was stuck so tight was the bottom bracket axle had a really poorly machined flat so the pin had deformed when it was first pressed in, accommodating to the ridges in the axle flat.
There's probably a better way, but what I did was saw the pin off flush, then drill a shallow hole in the end of the sawed off pin to center a punch. I supported the crank in a homemade wooden cradle clamped in a blacksmith vise (so the hammering wouldn't trash the bearings -- there might be a sketch in the Anybody's Bike Book (??). Along the way I kept trying to dribble/tap in a bit of penetrating oil, and I tried a propane torch, but in the end it was the hammering that brought it out. If it had not yielded to reasonable force, I woulda drilled it out from either end with small, then larger bits.
Reid Fisher That Peugeot UO-8's no longer in San Martin, Calif.