When setting a passcode from the menu, or entering a passcode at the passcode screen, pressing the white button causes the music manager to pop up. You then have to back out of the audio manager with the B button. I set the password to my skins menu to WWWW just testing and everytime I hit W I had to back out of the Audio Manager.
Edit: The Audio Manager doesn't pop up if you press the White button at the system password screen when first booting. Anywhere else it comes up.