I’ve just released an update allowing you add your own songs to the practice piano.  The format is documented here: http://www.souvey.com/musical/

Because this is only an experiment, the format may (and quite possibly will) change in the future, but if it does, I will release a simple program to convert to the new format, so rest assured you will not have to rewrite anything you create for this version.

If you come up with any interesting creations, email them to me, and I’ll add a directory on the format page of songs other people have created (although anything I provide on my site has to be legal and can’t be copyrighted).