it's more effective on a square taper dude. just take the bolt out an ride around for a bit. giving good pressure on the cranks. keep an eye on it though. don't want it to fall of while ur riding.
failing that, boil the kettle..... pour the water over where the crank joins the bb. that'll hopefully loosen it further. then ride around on it agen. (or no nonsense, get a blowtorch on its ass an take it to town)