Here's a homegrown way to set minimum air that I learned with carbs and still works today. Get a strip of paper about 1/4" to 3/8" wide and maybe 5" or more long. Open the throttle and insert the paper into the throttle bore past the throttle plate and shaft. The paper should be perpindicular to the throttle shaft. Release the throttle and gently try to pull the paper. If the paper has a slight drag then the throttle angle is ok. If it's too tight you risk stalling and a sticking closed throttle when the engine's cold. If it's too loose you risk having a high idle the ecm is unable to control. Ensure IAC counts are 30-35 and tps volts are below .75 and you're usually good to go.

If you want to set minimum air while the engine is running there are a few ways to do it. You can remove TPS or use a substitute TPS to fool the ecm into thinking the throttle is closed, then increase engine speed slowly until the ecm / pcm tries to command the IAC all the way closed. Disconnect IAC, close the throttle, and check your RPM. Or you can get an IAC test tool and use it to drive the IAC closed. Or you can get a special rubber plug designed to plug the IAC passage (known as a dog turd to GM dealership techs).