To be honest I don't know enough about THC or Plasma related stuff really to confidently advise.

If all your wanting to achive is to probe the surface then retract to a set height along with zeroing DRO's etc then that's easy enough done but you'll need to either alter an existing Macro like M3 or create your own. This macro reference you then have SheetCam insert into the code it produces at the points it's needed.

If your wanting proper THC in that it follows a set distance from the surface then that will probably be differant matter.?