Just can not put it back in there, that is what I was looking for myself.I think if you dump and extract your code.bin from the update and patch it with these tools it should work. I remember ShinyQuagsire saying he made SaltySD region-free.
For SaltySD you just run one command at this point.I'm not sure what you mean by patching? is there a program like an exe to run this? I'm not familular with python or anything like that. would that even work on old3ds because of RAM issues? To be honest I think just patching the dlc CIA (since the music is loaded from there anyway) would work best.