A modified version of the the following techniques will work.
http://www.cnczone.com/forums/showthread.php?t=56079
As long as Mach3 stays in the canned cycle until the end of the burn the
VB logic can take care of all of the control.
Just say where you want to burn and how deep.
On a vector by vector basis.
Mach3, from within a
VB loop can move any axis according to whatever logic you can invent. Stay in the loop until the burn is finished, or the abort button is hit.