Grandpa Moses and the Cat who Pooped in the Toilet

Family lore has it that Grandpa Moses had a cat that he had trained to poop and pee in the bathroom toilet.  After his cat had "done its business" in the bathroom, the cat would go to Grandpa Moses and "meow", a "meow" asking Grandpa Moses to flush the toilet, the one thing Grandpa Moses had never been able to teach his cat.  Does anyone know how to train a cat to such tidy habits?