Once you have done this, the whole console is temporarily unlocked and you can connect it to your home network and copy files to it from your computer via FTP. You start the game and load your save file and the console freezes, then switches to a new dashboard, with the security removed so you have full access to the console and the hard drive. Modding the Xbox requires you hack the console by loading up a specific game DVD from a list, and having a copy of a modified save game file to use.
This one sounds complicated, but it's not as bad as you think.
