The REAL Way To Open The Secret Save Menu:

All you have to do is bring up the submenu at any time by pressing the + (plus) button. Then press and hold the - (minus) button and tap up on the directional pad. This works with both the Wiimote and the Classic Controller. As far as I know you can't do this with the GC controller since it doesn't have a button that acts like the - (minus) button.