I just finished up a script that allows the editor to quickly and easily make custom formations ;D. Basically you give X/Y coordinates for each member of the squad, relative to the leader. So, giving #2 (-10, 23) would make him stay 10 meters to the leader's left, and 23 meters in front of the leader. It's easy and it works great! It works with AI squads, with squads led by the player, and even in squads led by AI, and later taken over by the player (after the leader is killed).
I'm about to post the script, but if anyone has any suggestions of formations to be included in the upload, go ahead and post them.