Welcome to the forums, seldom
The only way I could see would be to make your own addons.
However this would mean that everyone would have to download your addons before being able to play the mission...
The names displayed are the class names of the soldiers, and to my knowledge that is the only way to change them I'm afraid...
![Wink ;)](http://www.ofpec.com/forum/Smileys/NewSet/wink.gif)