Because I know you want to hear this --
For the last month or so, Bill had been using his litter box as it sat on top of the toilet seat, w/the lid up. Yesterday I removed that and bought a metal mixing bowl and suspended it (via duct tape -- most indispensible tool ever) in the middle of the toilet and filled it w/some litter. I stayed home all afternoon to hopefully catch Bill when he uses the facilities, because I need to teach him how to squat on the seat w/all four paws. (Being a pet owner is demanding, eh?)
Unfortunately I missed his business-time (and basically wasted an entire afternoon at home), but fortunately I came home from a party to find he peed very properly in the inner bowl and didn't spill a drop. That's an encouraging sign, at least! He apparently made the switch from box to bowl with no problems.
The next step is to fill the bowl with decreasing amounts of litter. But before I do that I want to make sure he knows how to squat. So this might be a month or so of me spending my time at home in front of the bathroom, instead of out in the living room, to catch him on his bathroom run. Nurse, cancel my one o'clock ...