Have you ever heard of a company called Bauman? They make something called the Bauman Transmission Controller. It's a stand alone computer that controls just the transmission. We have used them on Fords before, but I would bet they could do something for you. May be worth a call to them to see what they could do and at what price. That's the only place I can think of that could help you.
Baumann Electronic Controls Home Page
Laters,
Brian