Thanks to Chupu for pointing me in this direction, but this is an absolute life-saver. Basically you click on the mob that you want to shackle (or sheep/fear/*add your favourite targeted CC here*), then you click on the button you have set up for the macro. It will (a) carry out the relevant bit of CC, (b) set it as your *Focus Target, and (c) announce what you are CCing.
#showtooltip Shackle Undead
/cast [target=focus]Shackle Undead
/raid Shackling %f
Obviously you will need to replace the orange bits with your particular spell, and you can type in the green bit whatever you want (sheeping %f - keep your mitts off!).
(Note: %f means that it will output the name of whatever your "focus" is .. so if you are shackling/fearing an undead hamster from hell, "fearing %f" will report to raid chat "fearing undead hamster from hell".)
*Focus Target - this is really cool. It means that, in effect, you can have two targets. You can target the main dps target, yet as soon as your CC breaks on your focussed target, you can click on the macro button, and despite still having the dps target as your main target, the CC spell will be cast on the focus target.
Recommended more for Shadow Priests than the healing specs, although in a pinch you could Mind Control a healer to do the healing of your group for you, whilst taking them out of the group of mobs you are attacking.
Macro Explain-o-matic: http://www.macroexplain.com/mg7
This macro will focus your target as well as cast Mind Control on your focus target, Right click will remove the focus
#showtooltip Mind Control
/cast [button:1,target=focus,exists]Mind Control
The best tactic is to actually start the pull with MC (after any saps, etc) - this way the target you have Mind Controlled becomes the target of the rest of the mobs in the pack, giving the rest of your party plenty of time to cast any additional CC and to get into position. Be aware that if you move the mind controlled mob away from you, there is a possibility the MC will break due to distance. Also be aware that, if you are tempted to throw a mind controlled mob off a bridge/cliff, etc - it will either come back, together with lots of friends, or respawn later on when you're not expecting it.