About the only set-up I'm personally familiar with besides a front hub motor that works on a back-pedal brake bike is either a stoker monkey type set-up where the pedals are not freewheeling when the motor is running and the motor has low enough cogging torque that its possible to back pedal turning the motor backwards as well in the process (have to fully release throttle to brake) or a left side second chain loop drive using one of those special brackets that clamps around the center of a standard size coaster brake hub (and some two and three speed hubs as well) with a spider assembly through the left side spokes to a large drive sprocket mounted just on the outside of the spokes. The specific mid-drive your asking about will not work because it has freewheeling pedals so you can't back-pedal with it.
Is your back pedal brake bike a single speed or is it a multi-speed IGH with coaster brake? If its a muti-speed IGH with coaster brake do you need to run the motors power through the gears (usually if you must climb bigger hills with smallish motor) or not?
Need a little more info.
Also, you do realize that single rear wheel brake on a motor assisted bike is a potential safety issue because of the greater speeds involved means you usually need better brakes then that, also if you have to panic stop are you sure your going to remember to release the throttle before trying to back-pedal to brake? (Especially an important safety question with a non-freewheeling crank stoker monkey type system.)
