There's been speculation on this "cheat" in a few of the mailbags, but if you don't want to root through them, I'll give you the gist of it.
After these discussions dragged on for many weeks, it was found that the "select code" only seemed to happen on emulator versions (which is why TMK staff and other sitegoers couldn't get it to work.) The best theory of why this happens (that I've heard) is that the emulators toggle certain tags that normally wouldn't occur so on the actual system. Some of these tags may initiate a debug mode, a feature particular to certain design systems. Therefore, the game thinks that the emulator is one of these systems, and includes the debug attributes (the select code.)
Aid