Tony,
The way I set it up is to use, say, the turning tool and jog it to touch the end of the bar and set the Z on the Mach display to zero. Touch the tool on the OD and set the X display to zero. This gives me the 0,0 from which all other tools are displaced like the origin on graph paper. For example, I would then jog the drill to the centre of the bar end and read off the X and Z values.
These are then used in a G00 move in the G code. Repeat this jogging to get values for all the tools and write all the G code setting depth of cuts and feed rates and making sure there are no collisions.
Cycle the G code cutting air, make any corrections, then cut metal. All that remains is to tweak the code to get exact sizes and the job is done!
Hope this helps.
Regards,
Ian