Keeping this short, heres the steps, no idea what its useable for but gotta be something
1. Que and join Dungeon Finder
2. Leave dungeon finder group and instantly alt+f4 out of the game
3. Open wow and log in to your character
4. ???
5. Profit
Enjoy
EDIT: I can't seem to leave the instance trough the portal
EDIT2: Can't leave the instance by either HSing or joining a new dungeon finder group, after relogging while in the new dungeon finder group i was able to leave trough the portal
EDIT3: While HS in on cd, using the stuck function will kill you and release you in the same spot, but not allow you to ress