That is basically how you hotwire one of these trucks. He needs to see if there is power supplied by the ignition switch when the jumper isn't in place. However, for the purpose of running the motor you can use the jumper and leave the switch off.

1951 GMC 1 Ton Flatbed -- It is finally on the road and what a great time I have driving it!
1951 1 Ton Completed

My Chevy Master 4 Door is on the Road!