WoWDB

The Shado-Pan prisoners are in rounded wood cages in the Forward Assault Camp area of the dungeon. Your group will need to clear at least through Commander Vo'jak in order to reach all of the prisoners you'll need for completion - the gate barring the rest of the assault camp will not open until the mantid is defeated.

Another thing to note is that freeing a prisoner will not dismount your character. This is important because a majority of dungeons will not bother clearing the trash mobs out of the way of reaching the prisoners. Turn in Take Down the Wing Leader to Shado-Master Chum Kiu first; it requires that you choose your reward. Then go back and free what prisoners you need and run like the dickens back to Chum Kiu, turn in the quest, and drop from the instance party.