I've searched, and all I see is replacers. It would be nice if there was a mod that created a customizable character pool for enemy units.
I just use the mods, so I don't know if it's possible or not to do so, but I think that would be a pretty cool idea. The idea popped up from the Mass Effect Husk replacer from the lost, and how it (at least for me) is bugged in a way that it makes texture for the head not totally fit so you see a human head underneath. I was thinking it would be nice if you could just open a customization menu like with soldiers and change the head to like an invisible head or something.