I struggled with this exact thing ( read my old posts ) for awhile. Its very easy now. Both the dueling ( grand melee ) quest and the ones at the gate. Just like someone else mentioned, I do the Grand Melee quest with one mounted and the rest assisting on the ground. for fun ill pop my Fire Eles so they can help anyone else who happens to be dueling there 8). For killing the Commander and Lieutenants I have the following macros. In Bindpad i have /focus playerx /follow focus /assist focus ( bound to F4-8 ). That is the macro i always use ( vehicle mounts or not ) to switch my focus, follow that new leader and switch the new leaders screen at the same time ( PiP ) Then my follow macro ( same one I use all the time ) is /target focus /follow focus /assist focus and I have that bound to my tilde key ( ` ) So while mounted i can target the mob/player with my leader and hit that. now everyone is assisting the leader. Easy stuff!

As a side note, these macros make it so i can drive a demolisher and have 2 of my guys in the seats, when i hit that macro i can target people behind me trying to kill my demo and kill them. I only do that when i can not get 5 demos.