Well, the most straight forward way would be to edit them into the map file through a text editor (though it is quite painstaking). The only other way that I can think of is to remove the default civs in the editor, start a new game with the civs that you want, and then move them to where you want them to be (don't forget to clear their exposed FoW). Still, if there is an easier way, I would like to know!