I've never seen one as described that has definite on/off positions along with momentary. That doesn't mean there isn't such a thing though. If there is room for a two gang box, or even another single gang, how about a single pole, double throw, off position in the center, along with a momentary toggle switch? One throw could be the normal on/off and the other throw could go through the momentary.
Edit: I didn't post my entire thought process. Having a DPDT switch would prevent accidental bumping of the motor. I will admit to not having a clue what the machine does though. Maybe reaching down and flipping the wrong switch wouldn't cause any problems if it were to get paralleled in along with a SP switch.
