I'd say possible. The new game's soundtrack has been dumped and converted, so it can't be too hidden away. I haven't looked at the game files but if it uses Nintendo's usual streaming audio formats, there are converters around. So you'd want to extract the game files, locate the music files, figure out which is which and any stuff like loop points. Then obtain or record the tunes from the gameboy version, and convert them to the right format with the right loop points. Throw them in the right place with layeredfs, bingo bongo.