Hunter ground target.

Hello all, I am having a little bit of a problem running my 4 hunter priest team. I am able to run almost all of the cata regular instances at this time while i gear up for the heroics. My problem is trying to freeze targets before i pull. I am running my priest as my main since its easier to maipulate the hunters. I switch screens to launch traps per hunter. I was wondering if anyone has tried this or can help me figure out a macro to make for launching traps and possibly doing a round robin for ground target. I know you can place a ground target for mages and DK's but for some reaon i cannot get the trap launcher one to work. Please help. When i get this all working i would love to start posting video's on this.