I think dogs are more particular about where they want to plant their prized poopies, more so than pee. Watching my dogs in the yard, they will sniff all over that yard until they find just the right spot. They'll pee anywhere though.

Is your main goal to actually paper train or do you want to eventually housetrain? If you are trying to housetrain, then the only thing paper training does is teach the dog it's ok to go potty in the house. A crate, regular routine, and lots of praise will be needed to properly housetrain. Otherwise, a doggie litter box and jiena's method is a good idea. If only they made litter boxes big enough for Pit Bulls.