Just in case anyone has the same problem I did trying to figure this out, this is what I did....
The starter relay trigger wire (TN/RD) needs a 12V+ signal to trip the relay and send power to the starter solenoid. All I did was tie the trigger wire into the wiring coming directly off the "start" key switch wire (RD/LB) under the dash. I also put a 25A inline fuse between the wires.
There is obviously a better way to do it just under the truck, but this was the best way I could do it on my haggard up truck.