I am not really familiar with the standard lathe screenset so I don't really know what the button in question is meant to do.
If you simply want to home the Z in the normal manner, as you would with a mill, and as I do with my own lathes, then try
DoOemButton(1024)
That should home the Z in the normal manner, ie move at the set homing speed %, trip the switch and back off until switch is closed again.
Hood