u need two things...

one is a tool that perforates the wall paper to allow water to get through. the other is a steamer that greately accelerates the absorption of water to loosen the wall paper.

Another trick is to have a lot of water and wet towels because you need as much time to clean out the glue as to scrape off the paper.  You don't want to do it again when the scrapped off paper gets glued back to the floor it falls onto.