Hey Brian. THe process is quite easy. First you use Screen4 and edit the buttons for zeroing the X,Y or Z. Give the Zeroing Buttons shortcut keys. Then you use Key Grabber and assign those same shortcut keys to the different buttons on your controller.
With setup, I zero all three axis and then run the GCode. Handy to have is to assign the Esc button to one of your buttons that way you can stop the machine no matter where you are in the shop.
Hope this helps.