Installed today
After reading an article on page 36 by Robert Patton, I installed a kill switch on my 2004 today. The hard part was finding the ideal place for the switch. It took 15 minutes for the splicing into the ignition wire and another hour to remove the dash, run the wires, install switch, and put it all back together.
Not sure about the 06 wiring but the break sensor sounds like a great idea.
Had a kill switch on my 2002 and it was funny to watch the salesman try to start the truck after I traded it in. (It was 2 years old with 15k and the mechanic didn't check it out) First I told him "now you know why I'm trading truck in". Then after starting the truck for him I said "you really don't know much about the 2002's do you".