A miller of PCB's should be prudent...

So after probing, I have the (bad .. ?) habit of trying to mill the PCB pattern in first instance slightly to high/in the air, by setting the Z=0 height slightly to high.
After milling this air process I want to go deeper by adjusting the Z=0 height.
In MACH3 I normally take thereafter " RUN FROM HERE" etc.
But in the AL created file, this seems not possible when I take the place were it normally stops after the probing procedure to change probe/mill.
Question: How to accomplish several " millings" with increasing depth, while -not- continuously repeating the same probing ?
Hessel