I use an FTL setup. I prefer this method because it leaves the focus target available for CC. Before approaching a group in PvE (or if you're stealthed like us druids before approaching a team in PvP) then you can set up your focus targets for each slave. From then on, whenever you hit your "mass CC" button you will find all your slaves casting at their appropriate CC target. If you didn't have focus available to do this, then I'm not sure how CCing the middle of a battle would be possible.