Ju87 Stuka using CEM

[Plt Off JRB Meaker]

When flying the Stuka on CEM what is the control with 'S' marked on it situated between the throttle and radiator controls,is it the supercharger?

If so how should I map my control for this,'Supercharger next step' and 'Supercharger previous step' so this gives me on or off?

Is this the correct way to use it?

Any tips would be gratefully appreciated,just started getting to grips with the Stuka today,and going through a steep learning curveHe he

Thanks