I had never used an XBOX before attempting this mod, so I had a little trouble initially. When I was supposed to copy the installer from the memory card to the hard drive using the XBOX’s media manager, I was unable to copy it– the only option I had was to delete the file.
The problem was that you select the game you want from the vertical list, then you have to navigate horizontally to select the file itself. So in my case, I hit Down Down Down until I got to the installer, but I was neglecting to push Right to select the file. Once I hit Right, I was able to copy the file without incident.