You will generally want to change the leader's model file found in (..\CivilWarII\CW2\GameData\Models\) although you may also want to look at the leader's unit file, although there is very little defined there (..\CivilWarII\CW2\GameData\Units\) .
Many leaders have up to 4 model and unit files, one for each rank, depending on which ranks they may have in the game. The model files all begin with 1-4 digits followed by 3 capitalized letters, denoting the faction to which the leader belongs, then followed by the leader's name. The lower the number represented by the digits, the higher the rank, but you will have to look inside the files themselves, because many leaders do not have lower ranks and some do not have higher ranks. For example, Cooper has only one model at rank 3, Hardee has two models at ranks 1 and 2, and Sherman has 4 models at ranks 1-4.
Basically there are 3 steps
- Make a save of files you are going to mod in a safe place outside the game installation.
- Edit the file(s) of the leader at the specific rank(s) you wish to change, being careful to only change the parameters of the characteristics you wish to change, and save it.
- Delete the Models.Cached and/or Units.Cached files in their respective directories, depending on which files you have modded. When you start the game again, it will recognize that the .Cached file(s) are missing, and regenerate these.
That's it. The game should now recognize any changes you made.
You may also wish to look in Modding AGE engine games
. There is a CW2 subforum, but since all the AGEod games use basically the same engine, any information on modding models and units there should be valid in all games.