Okay... I was about to try this out and then I realized that I need to override the .php as well.
My first problem with that is that I can't locate the Jetpack file that contains the html output for the slideshow shortcode.
My second problem is - again, I can't overwrite that output anyway.
I was thinking I would just create a custom template that would activate the slideshow... in theory, that should still work, shouldn't it?
I don't know... I'm getting so confused. I might just install a plugin and say to heck with it.
I just don't like any of the plugins because you have to enter all the metadata twice - once for the actual WP Media Library, and the second time under the plugin settings.
I was hoping to be able to streamline the process by using the native media library's meta data.