1. Unzip the file using a program such as WinRar, which can be downloaded from here.
2. Open DarthMod Empire Commander Edition file.
3. Copy darthmod.pack to C:Program FilesSteamSteamAppscommonempire total wardata
4. Copy user.empire_script.txt to :

VISTA C:Users(Your User Name Here)AppDataRoamingThe Creative AssemblyEmpirescripts

XP C:Documents and Settings(Your User Name Here)Application DataThe Creative AssemblyEmpirescripts

Warning! If you do not see these, enable Windows to show hidden folders