Custom PCs?

[Kuujis]

Well... Guys are adding whole bunch of JA2 mercs with their corresponding sounds, etc., so I don't see any reason, why the stuff you want could not be accomplished...

But, as always, there's a catch - you'll have to do this manually I.e. go to specific merc describing files and change stuff there. No out of the box in-game tools for that sadly...