flash need to have dynamic path for XML with Html Parameter

I have this flash mp3 player , and it read data from an XML file named "playlist.xml"
the code is :

if (xml == undefined && mp3 == undefined)
 {
     xml = "playlist.xml";
 

now I want this Path for my xml file to be dynamic and be in the HTML doc. so I can change it with php. can you please guide me how should I change my code to read the XML path from a parameter in HTML codes ?
p.s. My Flash file is in Actionscript 2.0

---