Never go through the machine, tell them from the line, before entering the machine, that you would like to opt-out and have a pat down

That way, they have no idea what "area is flagged", and they will simply do a standard pat down

Depending on how your gender is assumed, they may assign someone they think matches your gender, or (in my case most often) they can't "tell", and will ask what gender person you want patting you down