I wanted to be able to play mp3s from CMI Play w/o needing a server running, so I modified CMI Play.
NOTE: This is a hack. It works for me, but I will not be held responsible for anything that happens if you are inspired to try this out.
Open a _copy_ of CMI_Play in Orange's editor.

<declarations page>
use_server ["Get mp3s from a webserver"] : bool = false;

<album page>
1. change the variables:
var webServerName = ""
var webSiteName = "c:/path/to/mp3/directory";

2. find
and add this line after it:
var useServer = $use_server;

3. find the line:
fn = "[url]http://"[/url] + fn;

and replace it with:
if (useServer) fn = "[url]http://"[/url] + fn;

Now when you generate the website, when you click play your browser should ask whether you want to play the file in whatever your mp3 player is.