Using them is simple:
With the game-window selected, press the proper keys, then go to the terminal, type in the room-name (either "Manny's Office" or "mo" for instance), press enter, voila.
This is exactly the sort of thing I was looking for! I'm trying this right now, but something's not working right. I launch the game from Terminal (with "open /applications/residual.app") but once I'm in the game, neither "J" nor "cntrl + g" seem to work in this way. I'm pressing both in the residual game window and then clicking over to the Terminal window and typing the various codes found at http://www.grim-fandango.com/hacking.php
. But Terminal just says "command not found."
What am I doing wrong?