Here's what I do.
In your browser put the address http://api.steampowered.com/ISteamUs...380&format=xml. The xml file will display in your browser. Use your browser "View Page Source". Copy that into a file. I named my file "zorro.xml". Have both "zorro.xml" and "zorro.xsl" in same folder as next code and run that code.
This should style your xml file and display it. Instead of using
// code for IE
// code for Mozilla, Firefox, Opera, etc.
else if (document.implementation && document.implementation.createDocument)
resultDocument = xsltProcessor.transformToFragment(xml,document);
put it where you want.