So, when my son was potty training, and LOVED Thomas the Tank Engine, I made a little chart with a picture of a train and 10-20 blank circles. I laminated it, because I have a laminator, and because I was training a boy. I took the ad with the pictures of all the trains and cut them and ran them through a xyron sticker maker ($9.99 at Walmart). Every time he performed, he added a sticker.
Now, I'm assuming that since you are posting on a Disney board, that your little one likes Disney. You could do the same type of thing. Once the chart was filled, he "earned" the train that was featured. You could do the same sort of thing with a favorite Disney character. (I had sayings like "Peep, Peep, time to go Potty" with Percy, or "Going Potty Makes me Proud" with Gordon.) You would have to know Thomas to know that those are the types of things the trains say. Anways, hope that that helps.