In the gamestat/ sub folder where Dark Colony is installed, you'll find a few text files.
To change game settings like sounds and weapon damage, edit these.
Any text editor, such as Notespad and TextPad can be used.
A good file to start with is weapstat.txt.
For example, to get some pretty cool human troopers, change the first entry to:
% Human weapon 0 (1) 1 weapons 3 10 75 500 60 12 1 -1 -1 0 0
Editing these files are not very easy, and some experimenting is necessery in order to get cool results.
However, it can be fun.