I second Psychomuppet's concerns.

I'm running a Warrior, Pally, Shaman, Lock and Mage, and I'm trying to think of a good way to control my spells while keeping focus for crowd control.

My idea so far revolves around using a "main assist" from within my party. Probably the shaman since he doesn't have crowd control.

What i'll do is hit my target key with my warrior main (i even mark the enemy with a skull so i can easily see whether my other toons are targeting the correct target) and that sets my shaman to focus on the kill target. My support characters will have a macro set up to

/cast [target=partyXtarget,exists,harm,nodead] InsertSpellName [the X is the party spot of my main assist]

When I'm ready to change kill targets, I re-hit my target key. A problem here with using partyX is when a newcomer comes into my party and screws up my party order. You can't use [target=Toonnametarget], at least it hasn't worked for me.

For emergency spells where I need my toons to interupt or stun what my main is on I use the same macro except replace the X with the correct number for my main.

This will ensure that all my clones are focusing on my mainassist and only killing designated kill targets. My emergency spells will only hit what my main is targeting, and this also free's up my focus for crowd control on the characters that are able to CC.

I know this setup has problems changing things around when my main dies, but I can't think of a better way to let my toons CC other than focus.