How did you make that?
I edited the mission script with the help of Madman and Steman model ID list. For example I changed the leaders skins with the normal ones editing the ID number. I did the same to swap Edgar with Russell and the slingshots with the sledgehammers.
Then I changed their fighting styles and AI via ide. This only worked because the mission script doesn't give the leaders their boss fighting styles and stats (no override in other words).
Remember that this was done before the lua compiler was made.