There's a product out there called, DIF. You can find it in any wallpaper store. The Home Centers have it to. Also, get yourself a paper tiger while you're there.
A couple of notes ... Follow the directions exactly. Don't try to rush the job, or take too long. The water must be kept warm/hot for the DIF to work, and don't try to do too much at once. If the mix gets too cool, it takes longer to work because the enzyme in the DIF doesn't 'like' cool/cold water. Use a 3" spackle knife for scrapping. Buy yourself a 'paper tiger', and as you're perforating the wallpaper, be sure it doesn't get too gumed-up with wallpaper. Simply, keep it clear for maximum effectiveness. It's used to perforate the wallpaper so the DIF can get behind the paper. You don't need to go 'crazy' with the tiger. Just be thorought. ONLY push hard enough on the tiger to perforate the paper. If you push too hard, the plaster / drywall behind it will need to be spackled! If the wallpaper in question is the 'foil' type that's usually found in bathrooms or kitchens (moist rooms), carefully peel off what you can first, then use the tiger, THEN use the DIF. The foil paper doesn't absorbe the DIF mix at all because, well, it's foil. Really, if you have regular wallpaper that's peeling, go ahead and CAREFULLY pull off what you can there too, then tiger, THEN DIF. In short, the easier you make it for the DIF to get to the glue, the easier the paper comes off. When you're done, wet-sponge the walls with a fresh DIF solution to wash off the glue that's left behind. One thing I did was move the furniture towards the center of the room, then layed plastic along the wall, and put the DIF solution in a garden sprayer using a fine-mist nozzle to apply the DIF solution. You'll get enough back aches; this method is quick and comfortable.
This sounds like a lot but it's only time. And believe me, if you spend the time doing this kind of job right, it will pay off! Job preparation is the bulk of any finish job looking nice! Once you get the hang of it, it goes quick. I was able to do my first 10' x 12' room in about an hour. You eventually start 'working ahead' on one part of a wall while scrapping on another. And keep that teapot 2/3rds full and on low heat so you always have a nice, hot supply of water for the DIF solution. A little more DIF in the sprayer/bucket is OK. Get yourself one of those BIG sponges that are used for washing cars even if you're using a sprayer. You can find them at ADAP, Pep Boys, K-mart, or any store that sells car wax and wash 'stuff'. As I mentioned, you'll need to wash the walls when you're done, and having a large sponge like this is real handy. Good luck and if you get a chance, let us know how you make out.