Ok this is a guide that is guna show u how to view 2.4 NPCs and such (aka kil'jaeden and all that)
1. Download WoW Model Viewer http://www.wowmodelviewer.org/index.php?option=com_remository&Itemid=35&func=fileinfo&id=28
2. download the PTR clinent and install it
3. After youve done that go to your WoWtest Folder (default C:\Program Files\ WorldofWarcraft\WoWTest\) and open up Data
4. Drag patch-3 and patch-4 into your World of Warcraft Data Folder.
3. Open WoW Model Viewer up and you should have a blue screen with a bar to the left with Character, Creature Bla bla bla. Go to the top of the screen to Options then Settings
4. you should see a list of stuff... click add to the right hand side of the box you just opened and go to your World of warcraft folder and open up Data.
5. Double click on Patch-3.mpq And click open. Do this again for Patch-4.mpq and then Close WoW model Viewer
6. Open it up and the Creatures from 2.4 (sunwell) Should be in there!
To get back onto WoW you MUST remove patch 3 and 4 from your data folder. drag them somewhere you wont forget them like desktop.