Get a hole-punch kit from Harbor Freight, Home Depot, or your preferred tool shop. You want one that has a 1-1/8" punch.
You drill a small hole in the center of where you want the button hole, put your punch-out pieces on opposite sides of the control panel connected through that hole, then tighten with a wrench and it punches out a perfect hole right where you want it - with smooth edges and everything. Ken recommends spraying down the punch with WD-40 first, and that helps it go through even easier.
Haven't done it myself yet, as I haven't had the extra cash to buy a kit, but others have extolled its virtues here many times in the past...