How do I change the sound source in musescore.com？

museHub and various Soundfonts are good, but not good enough. I would like to be able to replace the audio with something else, like Noteperformer output, after uploading to musescore.com.

I can understand that museScore developers and carriers don't want people uploading things that aren't related to music, but custom accompanying audio can greatly expand museScore.com's audience.