I needed to clear this for my Shaman epic, and did it solo at 63. Here's the method I used...
First I repeated the black dire and gem turn in steps to max faction, instead of doing the CoM pages camping. Much quicker.
After I was maxed out with the final dire turn in, I came to CoM. Killed the captain for the first key. Then I cleared through the throne area, and headed up to the platforms. Platform 2 is locked. I cast lev on myself, and leved up onto the post on the guardrail right against the building on platform 2. I ran off the side and over onto the walkway. It was easy, and I was past the first locked door.
This brought me around to the 3rd platform, and another locked door. Neh`Ashiir didn't seem to be up(No ghost noises when pressed against the door). I did "/target a_black_reaver". It worked, and now I had the mob in the room on the far side of the door targeted. I sent my pet to attack. Pet pushed against the door for a few seconds, then popped through and engaged. As soon as he had aggro, I back up and spam the button to back off the pet. After a few seconds he pops through the door, pulling the reaver back to me. I dispatch the reaver, and Neh`Ashiir spawns. /target Neh`Ashiir, and send in the pet. Pull back the pet after aggro, and now we're fighting outside on the walkway.
Mission accomplished, no rogues required, and no ridiculous shrinking or illusion nonsense involved.

Dread Shield of the Slayer
Key of Torsis
Neh`Ashiir's Diary
Spell: Call of the Hero
Stained Fine Runic Spell Scroll
Torch of the Elements
Woodsman's Staff
