Switch Y-Axis with B-Axis, because Y on mightyboard is not working

Hello,

I have an Rep1 where the Y-Stepperpart on the Mightyboard is not working.

So i would like to use the Left-Extruder Stepperdriver on the Mightyboard 
to drive the Y-Movment.

Would the change in STEPPER_AXIS_HH_

enum AxisEnum {
        X_AXIS=0,
        **B_AXIS**
        Z_AXIS,
        A_AXIS,
        **Y_AXIS,**
};

Enought to reach the goal?

Thanks!
