1. Put your WoW in windowed mode.
2. Use auto-walk (usually by pressing on Numlock if you didn't changed your key bindings)
3. Right click on the name bar (don't know how to say it in english, it's the thing over the program with the name of the program and the minimize/close buttons)
4. WoW will freeze, as soon as you left click inside the game, you will have walked but if there was mobs on the way, they will have ignored you