I suppose the cheap, easy, way would be to go to the auto parts store and pick up a manual choke cable kit for an old carburated engine. You could put the cable on some point of the throttle system in the engine bay and run the handle under the dash. Pull the handle and the throttle will act as if you're stepping on the pedal. You should be able to lock it in place to high idle it. Very crude, but effective. We have a couple of older International trucks at work that have come from the factory like this and it works very well. It's what they did before the computers completely took over everything.