Ok, people. I'm giving up.
The more I tried to do this, the more I realized that toilet training was just not in the cards for one of my cats.
I reluctantly put the litter box back out and hoped Rex would continue to flawlessly use the toilet like he did, but alas he was temped back to the box.
I have since taken the Litter Quitter off.
It was a sad day, but I knew that what I did is truly what will make Pascha happiest. And boy was she happy.
She hasn't had a mistake since, and that has in turn made the family happy.