Hi,
if you can get your head around how Mach goes about it preparatory move you are more than half way home.
When you hit <run from here> Mach does a dummy run of the Gcode to that point so it knows what the modal settings
are and the position on the toolplath just prior the the 'run from here' line. Mach will ask to do a preparatory move to go
from where the machine is currently to where it needs to be to start at the line you have nominated.
As garylucas has pointed out; if the preparatory move is to a point above the work surface all well and good, if its below
the surface the tool will drive to that location in linear co-ordinated fashion and gouge your work or break something.
For this reason there are a couple of options within the Preparatory Move dialogue to overcome that shortcoming.
If at this point you think 'this must be a bug in Mach' you're wrong, its the way Mach is and you have to learn to use it as is,
no whinging and moaning...no one will listen.
Craig