Well, I see someone found the hidden page. *snicker*
If you found this, you are either a very bored person, or actually ended up reading the FAQ *gasps*. Anyways, here are some cheats you probably already know, but I put them up just for reference.
To activate the level select, go to the options, and enter the sound test. Press the "B" button on 00 and you will hear a chime. Press start to go back to the title screen. When you return, hold the "A" button and press "Start". The level select will appear.
This cheat has not been changed. To access it, enter the level select, and move to the sound test. Enter the tracks 04, 01, 02, 06 in succession and you will hear the noise of collecting an emerald. When you select a level, you will now have all chaos emeralds.
This cheat has also not been changed. To access it, enter the level select, and move to the sound test. Enter the tracks 01, 09, 09, 02, 01, 01, 02, 04 in succession and you will hear a chime. Highlight the level you want to play, hold the "A" button and "Start" until the splash screen disappears. If completed properly, the score should be a lot of hex.
Yeah, I know, it's a crap hidden page. But if I ever figure out how to change the cheats for real, you might be glad you found it. If you found this, please contact me so I know someone out there is bored enough X_X