To get Princess to go on her pads I would soak the pee up with it, then when she'd smell it I'd praise her like crazy. The same thing with the poop, though she almost always goes in front of the toilet still, instead of the pad across from it. I would also just give him a treat for acknowledging the poop outside at all. Pretty soon he'll think 'oh, this poop out here means a treat. hmm...'
Good luck, it is said yorkies can take longer than average to train & Princess proved that to be true. Just hang in there & be consistent.
