I just found the skins for the civleaders. So I am thinking change thoughs copy the other files, change the names and vowla you have a new civ leader. also just go in and change the text that they say.

If you take your time you can actually add leaders instead of replacing them.
The things you can mod right out of the box for Civ IV are outstanding! I love modding this stuff.

[Edit] Also included in the Leader stats are personality definitions. Like how they react to trade deals being cancelled and stuff. Really neat stuff for modders to mess around with.

Thats what I had ment. you copy it chage its name and then you get an animated civ leader with backgrounds.