this may help even though i dont play a DK

I run a palidan with 4 element shamans. i set up my totems on the left side of the room so the skeletons have to run through me and my conscencrate and just spam chain lightning and heals. i do have a keybinding setup that may help you. i have all their lighting bolts bound to E but if i hold shift and spam E 3 of the 4 shamans will continue nuking and the 4th will spam lesser healing on me. since chain heal isnt really needed all the time if any really when you have an actual tank.

When the ice tomb comes up its easy to spin the camarea around and just click it and have teh shamans nuke it. it has very low hp and should die in a second. As far as the adds are concerned do deathknights have an AOE that will get aggro like conscencrate where you can position yourself where they have to path through you and get aggro? either way just target the frost tomb and use your aoe's on the adds

I hope this helps

Hope