I have installed a little door that was made for cats in my wall that goes into the garage and made them their own little private "Potty Palace". That was the smell doesn't stick around IN the house. It's really easy to put in. The wall was only about 4 or 5 inches thick and I made sure there wasn't any wiring behind the sheet rock. I also installed some old foam padding in the wall that the puppies walk through so the aren't exposed to the insulation.
http://i2.photobucket.com/albums/y49...0/100_5578.jpg
On the other side, I made the "Palace" itself and pushed it up against the wall so they can just walk right in and right back out. It took them a while to get used to being able to walk through the door, but they got it now. Inside I have a 12 fluorescent lite on so they can see and my Mother made some minature posters for them to look at kinda like tehy are cards from other Yorkies. I know it sounds cheesy, but they like it. On top of their palace is a hinged door so the news papers can be changed daily.
http://i2.photobucket.com/albums/y49...0/100_5581.jpg