AFAIK there is no such thing. There IS one more side, sideEnemy, which is the side you're on when your rating drops below a certain points (=when you've killed X amounts of friendlies they start shooting you, or if you put their rating far into the negative using the addRating command). However, everyone hates everyone, including their own group members, when on sideEnemy, so although that's good for a DeathMatch-styled scenario, it's no good for group vs. group combat.
So no, I don't think you can really do this at the moment.
Wolfrug out.