Here are the instructions mlclark posted in another thread:
Quote
The prongs on the switch are labeled top to bottom, I, P and F. With the throttle closed, you should have no continuity between P-F and continuity between I-P. Slightly depressed gives no continuity between both of those sets of prongs and with it fully depressed (WOT), you should have continuity between P-F, but not I-P.

To adjust the switch, hook up the Ohm meter to I-P and place a 0.012 feeler gauge between the throttle stop and the throttle lever. Adjust the gauge until the point where the continuity is just established. Then use a 0.020 feeler gauge to make sure continuity is broken. At that point, it is adjusted.

It's really very easy to do, but you'll want an extra tps plug and several inches of the wires. I don't know how you might be able to access the TPS with your tester otherwise.