Fred IF you have home switches then you have what yoou need to setup HOME. It does not have to be at the switch positions. The Home/limits setup page you can apply an offset to the switch position to move the actual HOME to be anywhere on your machine.
That would be G30 home
You can also Specific where you want G28 home to be in setup.
NOW if you are talking USER Coordinates HOME then Move to that location and do a
G52 X0Y0Z0 OR
G92 X0Y0Z0 OR
G10 L2 P1 X0Y0Z0
and you have just set the USER home to 0,0,0
There IS one more option and that would be to create a Mcode that will set the Machine HOME at the position you are at. But you can ONLY set it to zero that way. AND I am not sure how any HOME offsets woul dbe applied.
Hope that helps IF not I will try again, (;-) TP