This is a guide to get the argent tournament mount out of the zone. It requires you to have the hack, XYZ, or Monstr Hack, both of which I believe can be found on this site.
If while in icecrown and mounted on your argent mount, you go to the coords: 74.2, 29.3. Once you are there, you are going to want to use your XYZ/Monstr hack to move south, through the 'sub zone' invisible wall that tries to demount you when you run through it. once through, you can then run around on your argent tourney mount.
This maybe useless, I havent found a good way for this to be useful yet, especially since when you go into the next area, all of the mobs disappear for some reason.