First, unlock Gill and Shin Gouki. 
Then, at the option screen hold L + R. 
Highlight Game Option and press Left, Left, X, X, Right, Right. 
Highlight Button Config and press Left, Left, Y, Y, Right, Right. 
Highlight Screen Adjust and press Left, Left, X, Y, Right, Right. 
Highlight Sound and press Left, Left, Y, X, Right, Right. 
Extra Options should now be unlocked.