Well itch does have a forum for finding collaborators though I don't know how many people check it right now: http://itch.io/board/10020/help-wanted
Also you can ask around on twitter (I'll make a tweet myself pointing here, hopefully you'll find someone)
Also also if you want; you don't really need to submit a game to the jam - you could make some compositions inspired by myst and submit them to the jam yourself, maybe offer to let others use your music in their jam games if you want?
I know it can be tough for audio folk to find developers to work with, but I do hope you can find someone and have a good time with the jam :)