You don't have to use any buttons for anything
Neither of the versions (2.0 is the one to have) have anything to do with turning the engines on/off and feathering. All they do is let you use several throttle axis (like the G940 twin throttle, or a CH/Saitek quadrant) bound to control 2-4 engines individually in the game itself. Without it, you're limited to a single axis and can't use the others to control more than one engine.