Maxi Pads inside the belly band. Get him neutered - if he isn't already...
Postive Praise and Yummy good boy potty treats. Peanut butter chips from the baking isle are a good hit
There are things like, the doggie potty - it is a dog turf inside potty system, and they even have a little fire hydrant, so you can train him to pee pee inside too!