You'll have to make changes to the descr_strat.txt in the "...\Rome - Total War\EB\Data\world\maps\campaign\imperial_campaign" folder. You could manage to make all those wanted changes in that one file. Backup the file before you change it, of course. Alternately, you could just start a regular KH campaign, kill off all your non-Athenians and then let the other two cites rebel.