I guess there are only two approaches-- try to kill the opposing general with the towers up, or grinding down the opposition at a choke point. I don't know if the first is possible, and it seems like it'd be a hassle unless you grab and hold a graveyard near to the fight. Otherwise players might be able to scatter your group little by little. The second seems possible at one of the choke points that are near a GY, like the ones just north and south of the Field of Strife, so long as you don't let more than one or two people get past.

Not sure if it can be done, but that's the spirit of multiboxing, isn't it? Doing crazy shit that everyone thinks is impossible.