I don't have the patience to train animals to do tricks..
I did good just teaching chomper that he has to go to the litter box and go to the bathroom before he gets out (Dusty just sort of grasped it after the first time I put her in there).
All I have to do is sit down in front of the cage most days, he knows that means I'm fixing to open the cage door and he'll take a drink of water then go squat in the litter box, then he'll run up to the cage door and stand up on it waiting for me to open it.
Took a good week or two for him to get the idea, and Is till have to kinda keep an eye on him, despite there being two litter boxes outside their cage, half the time he'll just go wherever, even right next to the box.