Sorry about the typo! I should add BTN_PREVPAGE and BTN_NEXTPAGE as aliases so either way is recognized...
Just for fun, you may also want to try setting up Player 2's buttons as a six-key keypad (of course, you'll have to move the shutdown button, probably to KEY_SPACE, and change KEY_A to not select a song) so you can have direct access to songs rather than navigating with the joystick. The best of both worlds, as it were....
To do this, try:
KEY_A = BTN_1
KEY_S = BTN_2
KEY_Q = BTN_3
KEY_W = BTN_4
KEY_E = BTN_5
KEY_OPENBRACE = BTN_6
KEY_SPACE = BTN_SHUTDOWN
And in the skin, set HighNumber to 6 and UseZero to False. (Just edit the SKN file with a text editor to change the settings.)
The two buttons below those keys have a couple of good possibilities, either to jump to the first or last page, volume up/volume down, Popular/Pause, Pause/Skip Track, Previous Letter/Next Letter... lots of good pairs here.
--Chris