I published a few more codes on smashboards.
http://www.smashboards.com/showthread.php?t=268148
But today I want to focus on a function: 0x8007923C
This function is run to decide between a stages music slots.
Known Registers:
r0: Sometmes its set to 0×00010000 after the routine is run once. When it is, modifying r4 = CRASH or no effect
r4: The stage to look for music from – 0×00 = battlefield, 0×1=FD,0x2A = menu, 0×4 = mushroomy kingdom
What this means:
I can possibly modify PW’s stage expansion code so you can link a extra stage to an existing stages music.