I just thought of this 10 min ago, and it works great.
I needed to go to Thunder Bluff, and I didnt have the flight path. I just ecided that I would speedhack + mountainclimb hack to get there quick from orgrimmar, but I realised that i would go straight through mulgore and people would see me. Then I remembered the Lag Manipulation guide posted by Zentek so I just turned on the lag, and hacked my way over there! Unfortunately I died when I turned off the lag, and my ghost was back in orgrimmar, but my corpse was where I turned off the lag in Thunderbluff! Of corse you have to run there again as a ghost, but you dont need to lag there!
So pretty much:
1) Turn on the lag
2) Turn on the hacks
3) Run to where you need to be
4) Turn off the lag (and die)
5) Release spirit (if you got D/Ced then log back in)
6) Run to wherever you stoped the lag as a ghost (still hacking)
7) Turn off hacks
Be alive again
9) Enjoy your new location!