There's nothing in Bitmelo specifically that can do it, however you might be able to get it working using the browser webaudio api. The files would have to be hosted somewhere else, and I haven't tested it out. It might not work though because the game is running in a sandboxed iframe.
https://developer.mozilla.org/en-US/docs/Web/API/Web_Audio_API/Using_Web_Audio_A...