Swapping files in Sonic CD from Gamecube Sonic Gems Collection

[EuroMIX]

Intro - FAQ - Rules thread says get to the point, so I'll try, but I hope this is the right place because I'm not sure what the best forum for my particular question is.

I want to try swapping the music and videos for Sonic CD in the Gamecube Sonic Gems Collection to use the Japanese music and videos over the the US version so I can play an English copy of SGC with the Japanese/European music. Essentially swapping out one copy of the files with the other, renaming where necessary.

I've gotten as far as extracting the CVM files containing the game files, and then I can extract the music and videos files from that, however I cannot seem to work out how to replace the files and recompile the ISO. Just swapping the CVM file causes the game to freeze.

I'm not sure if this is possible, but figured it couldn't hurt to ask. I would appreciate any help anyone can give me.