To start WoW on all of your comps at once, place a shortcut on the desktop of all your computers and and hotkey the shortcut.

i.e.

Make a WoW shortcut, then
Right click the shortcut, under Properties there is a "shortcut" tab with a "shortcut" key. Put any letter you want in there (it will always start with CTRL+ALT however). Voila! if your keyboard broadcasts, hitting CTRL+ALT+hotkey will start WoW simultaneously on all computers!