A couple of things you may consider, (or already have,) is that (1.) when the TCU is in power mode it tends to hunt for gears, and (2.) the "power mode" which is caused by hot ATF may not be the same power mode that is caused by rapid application of throttle.
In normal operation, there's a margin between how much throttle is needed to get a downshift and how little throttle is needed to get an upshift. This 'null zone' keeps the transmission from switching gears at the slightest change of throttle. In power mode, the 'null zone' becomes very narrow and almost undriveable.
The next time you're at freeway speeds, romp on it and get the TCU into power mode, then abruptly let off the gas for just a second - maybe a couple of times. Notice how quickly it changes gears? It's like an annoying hiccup. If you do this a few times, you'll find the transition point (where it shifts) on your throttle pedal. If you hold the pedal at that point and just wiggle your foot slightly, it'll jump back and forth between gears like crazy (as long as you're in power mode.)
You can do this at low speeds too, but it's a bit harder to do as the TCU goes back into normal mode rather quickly. Power mode works very well if you just want to accelerate, but the TCU gets very confused if you want it to do anything else.
I think you'll find it very undriveable. Don't get me wrong. Experiment with it. It'll probably be a pain to drive, but a lot of fun while you toy with it. If it works, you'll be a hero to many.
