I wired a normally open pressure switch inline on the ground circuit for the TCC solenoid and screwed it into the 4th gear pressure tap on the valve body therefore allowing for a 4th gear only TCC lockup and still running the power feed through the brake switch.
I don't like them coming on and off alot while driving, puts alot of pressure against the thrust bearing in the engine and pinging due to high compression in my case. The switches are readily available still from GM or there are a few kits you can install.
You can install the switch externally if you have a pre 87 (if I recall) or internally if not....
Here's a few:
http://www.google.com/#hl=en&cp=7&gs...w=1010&bih=531