I hate auxiliary units, I think of them as XP/Kill thieves. I generally just send them to put their noses in a corner somewhere and then use the "core#" cheat code to allow deployment of replacement units. But I've discovered that cheat codes kill any progress towards achievements. DUH, right?

What I'd like to do is edit all of the scenarios in the Grand Campaign (and probably all the other campaigns eventually) so that any aux units are deleted and the core is increased by the same number of units. Of course, I am making the assumption that editing the scenario won't kill achievement progress. If editing the scenarios stops progress on achievements, it's a waste of time for me. At least it is at the moment.
Does any information exist on editing the GC scenarios? Or could anyone offer some advice for an absolute newb on where/how to start?