Dance Dance Revolution 3rd Mix
  
Playstation

  

Step Step Revolution(SSR) Mode:

  Once unlocked press Select in the title screen or in the mode selection screen.

  

  Remix Mode:

  Once unlocked press Select 2 times in the title screen or in the mode selection 
  screen.

  

  More Music:

  Keep playing the Diet mode for a few times then exit the game and you'll find 
  new information. Do this several times to have even more music. 

  * Tip: You can play this music in nonstop and remix mode. 
SSR Mode (for new player or without saving the game):

  Turn on the power & wait until the screen say 'Dance Dance Revolution 3rd Mix' 
  & quickly press: Left, Left, Left, Right, Right, Right, Left, Right. 
Remix Mode: 

  After you have accessed SSR Mode, Press: Left, Left, Right, Right. 
 
Thanks to Revolution readers NH and Ian!