But if you want to use it without mod manager then you can just goto the location of Scripts of Empire which Vista and XP are different. Vista is Users\XXX\AppData\Roaming\The Creative Assembly\Empire\scripts. (Not sure for XP). Then open the user.empire_script.txt and append this on a new line. (If there is none of this file yet then create it and put that as the first line)
Code:
mod familytreemod.pack;
But this is what Mod Manager does for you making it easier to quickly change mod load order and which mods to use.