Add WP Audio Player, Standalone to Zen Cart, v 1.3.9h
Example site: http://www.100YearsOfMusic.net/
So far this works on FireFox, Chrome, Safari & Opera for Mac (tested Feb 16, 2011). GOTTA CHECK PC browsers!

1. Add audio-player.js file to site. It gets added to the head section of the site by adding it to the jscript folder (upload to: root > includes > templates > theme245 > jscript):

jscript_audio-player.js (MUST add the jscript_ tag to the front of the file name in order for it to show up in the header of the site)

2. Add player.swf file to site. (upload to: root > includes > templates > theme245)

3. Add to tpl_header.php file, line 196, (upload to: root > includes > templates > theme245 > common):

[code]<script type="text/javascript">
AudioPlayer.setup("http://www.100yearsofmusic.net/includes/templates/theme245/player.swf", {
width: 290
});
</script>[/code]

4. Add MP3 directly to Zen Cart product page via Admin:

[code]<p id="audioplayer_1">Audio Player 1</p>
<script type="text/javascript">
AudioPlayer.embed("audioplayer_1", {soundFile: "http://www.100yearsofmusic.net/media/pops-song-snippet-the-home-team-band.mp3",
titles: "Pop’s Song",
artists: "The Home Team Band",
autostart: "no"
});
</script>[/code]