all credit goes to daenius over at xbox360a.org
this is taken from his achievement guide which he gives this methods credit to wilson1874
all you have to do is use 2 controllers. Make sure you are controller one, then move to the oppositions team and make controller two go on the team your using, then all you have to do is FORFEIT the match with controller one and then keep on doing it as you will win 3-0 making the other team forfeit until you Qualify gaining all points."