Yep. This trick has been around for a while. I think the Grand National guys made it popular as there were problems with the turbo cars getting them where they wanted them. I put one on a 1984 Grand National T-type car.
Don't know if the wiring is the same, but it is rather straight forward and simple. When you disengage it, you can punch the throttle and spin the engine up faster while at moderate cruising speeds. Your gas mileage will go down.
Try a company called Painless Wiring, don't have the web site handy sorry. When I installed my 700r4 I used one of their kits for TC lockup, it's not the one you want but I do remember seeing a wiring kit to control that. Even Jeg's or Summit might have one.
The guy I bought my '81 from years ago put a switch in himself. $3.00 switch from Radio Shack and wired it into the switch wiring at the brake pedal. Nothing special needed. I may have the schematic alteration he used in my Shop Manual. I'll check. Btw.... it works perfectly. Run her up to 50-55, hit the switch....and plop. One locked in TCC. The switch also has a 12V light in it so you always know when it's on.
I also asked a friend that is a trans. rebuilder...and he said to be careful not to run it too hard and cause overheating and clutch failure..But he said that was just in extreme cases..like trucks pulling a load. I guess you interupt the ground wire going to the tc. Does anyone know which one that is??