Quote from Farmbuyer1) Start the game client with "-console" on a Windows system (via command line, add to shortcut, etc), not sure how on a Mac.
Figured it out on a Mac.
1) Open a terminal window and navigate to your WoW folder
2) Type "./World\ of\ Warcraft.app/Contents/MacOS/World\ of\ Warcraft -console"
Rest of the original instructions work from here.