That seems a rather clunky way to have to do things, is that the way Tormach told you to do it?
I think I would be tempted to load the demo version of Mach on another computer and load the xml that you are using on the machine into that computer, change the setting and close Mach. I would then rename the xml and copy back over to the machine and load the modified xml and see how it goes, if its all good then you could make that xml your default for starting.
Hood