warrior tank + 4 shaman:

What I do is I have a seperate button that simply causes my shamans to assist my warrior. (F9 in my case, on Logitech G-15 it's easily reachable without moving my hand.)

Then my q is sunder. (And modifiers and whatnot, I could post exact macro's but I'll give you a basec rundown.) And for my shamans q is LB . I have ES, FS for nature immunes, etc on keys I don't overly use while tanking on my warr. 1-4 is healing for my shamans, each button is another shaman healing with [target=focustarget and then [target=focus]. Either heals my warrior or another shaman if my warrior has that shaman targeted.
I can apply a few sunders before pushing the target for my shamans so they start dps a lil later.

For PvP you could just put the assist on q as well.