I'll be producing custom mercenaries for your game utilizing GRM!
I have a BETA package available for any brave souls. It adds four Mercenaries.
http://www.nexusmods.com/galacticcivilizations3/mods/18/?tab=2&navtag=http%3A%2F%2Fwww.nexusmods.com%2Fgalacticcivilizations3%2Fajax%2Fmodfiles%2F%3Fid%3D18&pUp=1
Notes:
The Readme says you need GRM 3.0... this is actually a lie now that I think about it.
This adds 4 Mercenaries to the pool, with a weight of 50, the default weight is 25, so you should see these frequently!
The 4 mercenaries are basically copies of existing ones, but generally with lower costs or better stats/etc. I've just been fooling around figuring out how everything works.