I saw a thread o this topic, but I don't know if it was on this forum. There was a way to take a ground wire connected to a switch and ground the TC in lockup mode manually when on the highway. You just had to remember to turn the manual lockup off when decelerating.

 

I think Infidel (bill) posted on this a while back either in this or the performance forum with a schematic of the wiring as well as how to make it a little more user friendly with a 3 position switch IIRC.. Much luck in the search?