Quote Originally Posted by Karen
If you need to, keep him on a leash - attached to your arm - at all time. Take him outside ten minutes after he eats anything, and stay outside until he "does his business" - you may get bored out there, but it is important to get him trained a soon as possible, so he doesn't get the idea that doing his business inside is okay.

When he's outside and does his stuff, praise him like crazy.
That's what I was going to suggest too. When I got my min pin, Charlie, he was 2 years old and not a bit house trained. I always kept him on a leash, even in the house. When he couldn't be on a leash he was in his crate (when I was in the shower, or when I had to go to work, etc.). Keeping him on a leash outside while training him will also help (even if you have a fenced yard). Praise him when he goes potty outside, but don't scold him when he goes inside.

Also remember that he is just a baby and he can't hold it too long. He needs to go out often. He also shouldn't be left in his crate longer than a couple hours.