Machine home zeroing with no motion from G code.

Think you could sneak in a G code for no motion machine zeroing? G666?

About 5 minutes after I left the computer I realized I may have misread your original question.

But it seems to me you may be able to do what you want in hal.

As your spindle is a open loop stepper..

Take signal going to your spindle and send it through a component with hal before going to the spindle drive.

Create a User Defined Commands such as M102, M103 use these commands to toggle the spindle signal on and off to the spindle drive.

So if stopspindlerotation = "no" the spindle signal goes to the spindle and if stopspindlerotation = "yes" the signal does not.

Insert M102 in your g code when you want to rewind your spindle without rotation.

Move the spindle to where you want in EMC without rotating it.

Insert M103 in your g code to turn the spindle back on.

RickG