First it has to be noted, if playing multiplayer games you need to have the same scripts so use it with caution. Be sure to backup the Data folder before start modding and try to edit one file at a time and test that the game still works.
Commanders - Europe at War has 5 scripts that can be edited to change many aspects of gameplay and also AI.
unit_eng.txt - all the unit data
technology_eng.txt - every tech level and its effects
terrain_eng.txt - terrain effects
leader_eng.txt - list of leaders & their abilities
general_eng.txt - various rules that you can modify to change general game behaviour
Although these files are installed on your PC as text files we find it much easier to edit them in excel format, and then save them as text files. The exception to this is the general_eng.txt which is only in text format. If you want the excel version of these files you can download them from http://www.slitherine.com/files/ceaw/ce ... s_data.zip
To edit the excel files all you have to do is
1) Open the excel file (you can download a free program like OpenOffice if you do not have excel)
2) Edit any numbers
3) Choose "Save as", Unicode-text (.txt) and overwrite the corresponding file in the data folder of CEaW.
We advise you to change one file at a time and test after each change to make sure everything works as you would expect. If you have any questions we'll do what we can to help. Bear in mind we cannot offer full tech support for games that are crashing using modded data but we'll do what we can

If someone creates a mod and wants it hosted then let us know and we'll see what we can do.