I'm pretty sure you could litter box or paper train him. I know at the pet store there are puppy training pads that apparently have a scent that makes the puppy want to go where the pad is. It is supposed to be an aid in house training. I have never tried them before so I couldn't tell you how well they work.

It might take more time than if you were training him to go outdoors though since it's a much more limited area. Good luck!