Hi,
Squaring the gantry is a process that is offered (usually) by the motion controller, not Mach4. In the link you posted the squaring
parameters are set in the HiCon plugin....not Mach4 at all.
I am not familiar with the HiCon but am very much more familiar with the Ethernet SmoothStepper. It too offers gantry squaring.
It is possible to program Mach4 to square a gantry. Quite some months ago I was involved in a thread (Mach4 board) which concerned itself
with 'slaving' and 'un-slaving' motors on a gantry programmatically. This allows you to temporarily 'unslave' a motor, jiggle it back and forwards
to square the gantry and then once squared 'slave' it back to the master motor.
In the first instance I suggest you use the features/facility built into your motion control plugin. If that is insufficient then consider writing
some Lua scripts to do as you require.
Craig