look in data/world/maps/imperial_campaign/desc_strat.txt for faction starting locations, buildings, armies, etc. That is also the file you edit to unlock all the factions if you don't want to do it the normal way (finish any campaign (short or long) with one of the 5 starting factions) It should be pretty obvious what to change by looking at it. If you want directions look in any of the faction guides (any except the 5 starting factions) in the 'M2TW Guides' section on the front page of The Guild.