This works great, except I can't figure out how to change the song.
For anyone else having this problem, change the address listed in the readme or just replace
09 originals/09 Bonus End.txt
with the song of your choice, although you'll have to have the bonus game disabled. That was a coincidence for me. This workaround is really useful if you've done lots of stuff to your hack and reinserting this patch is impossible.
This works great, except I can't figure out how to change the song. Nevermind the included song, I couldn't get it to go past the title screen theme when working down and past the special world theme when going up. I can only use $01 - $09. this is in the owyicoin.asm file.