Now many of you might already know how to pull this off but basically you can kill the first 2 mobs in the instance 5 times every hour and you can do this solo. While it doesn't really give you rep that fast it'll speed up the grind and it's good if you're missing a very little rep from the next ring.
I have not tried to do this as a night elf but I think I can pretty safely say it should work.
So what you do is:
1. Run into the instance in a raid with someone but it's best to enter alone.
2. Stealth at the entrance and go forward to the NPCs
3. Wait till the mobs that automatically run to the NPCs to be killed
4. Go towards the first two mobs and use hand rocket / thrown / some ranged ability to pull them and sprint back towards the entrance with the mobs following you
5. You need to pull the mobs far enough so that they run past the NPCs that are supposed to kill them and then vanish/shadowmeld. Now the mobs should run and attack the NPCs with 900k+ hp and start getting killed.
6. Now you can just use your thrown weapon to damage the mobs a bit while they're tanked and damaged by the guards. Just make sure you don't pull aggro, you don't need to do a lot of damage and you still get the rep.
This might take a few tries to get it done perfectly.