What you use is wallpaper remover. Paint over paper never looks right and some years down the road, somebody is going to be mad at you when they--or you--try to take the paper off. It really doesn't take that long with most papers to take them off. If you had old paint or primer on before the paper went up, warm water will get it off. If it's vinyl coated, then you can just pull the vinyl layer off then finish with water. Five year olds can manage this part very nicely, whether you want them to or not. For some special cases--well attached old paper--you may have to use a "paper tiger" tool and the enzyme remover. But usually all you need is a sponge and putty knife.