Some time ago I wrote a CGI-Script, that I could trigger through a simple WEB-Request. This CGI-Script was just some AppleScript (through oasascript-command) to set up the server's sound-volume and for playing a sound through the command line-app.
I used a small example-app Apple greated (X-Code command line app-example) which is called Ascii-movie-player.
When you open a quicktime-movie using this app in your terminal, it trys showing it using ascii-characters, but it works with simple soundfiles (quicktime is able to play), too.
I compiled it for PPC so it should work, when Rosetta ist installed. For more info take a look at
http://hubionmac.com/wordpress/2008/10/alarm-ton-bei-aufruf-einer-website-panic- button-20/
There you will find a copy of the source and a compiled version (CGI-Alarm)
e.g. you saved the player binary at /usr/local/bin/player
do shell script "/usr/local/bin/player ~/Music/doorbell.wav"
should work