I do not use the air method as I am just too scared of 1) blowing something apart, and 2) not getting all the water out like the water that is inside the water pump. That is just me as many many people use this method to good results.
I use the hose that attaches to the fresh water tank to suck antifreeze out of the gallon and into the system. You simply disconnect the hose from the fresh water tank and place it into your gallon of anti freeze.
You then turn your pump on and pressurize the system. Then go around and open each valve until it runs with antifreeze. Then close.
This method is simple and will also protect your pump, natural valleys within the plumbing and the drain traps.
2006 HW256 (previous pup)
2013 Chevy Tahoe
Equalizer WDH 1000#