No you don't need an impact wrench and like stated, it's a bad idea. I have never esed one.
You need a clutch puller, and a clutch holder. If you don't have a clutch holder, you can use a bar and not damage anything.
YOu're clutch will probably be difficult to take off, I would just start by tipping the sled on it's right side, or the can side, take the clutch bolt out, pour aoubt 1oz of water down inside the clutch, wrap teflon tape around the threads on the clutch puller, and start it in. It should pop off once you get it tight and it shouldn't require much torgue, if it does, torque it in as tight as you can, and give a few good wacks with a hammer( the end of the clutch puller that is).
Good luck, it's not that hard.