A few months ago (patch 3.1 I think), Blizz added "Interact with Target" and "Interact with Mouseover" functions that you can bind keys to. Have a look in your keybinding screen.

So now you can:

1. Target a corpse with your master
2. Have your slaves assist the master to aquire the same target
3. Use your Interact with Target key

and the slaves will all try to loot the corpse.

It also works for interacting with NPC's such as quest givers and flight masters.