In the sample string in one of the examples:
// var xmlData : String = '<MonsterCollection><Monsters><Monster name=""a""><Health>5</Health></Monster></MonsterCollection>';
The XML is malformed and will throw an error. Secondly, there should be some errata listed on this page that states that Unity will give a monobehaviour error (even when using JS) when a class name inside of the script is the same name as the script file name. The stated examples use a naming convention that will display this error.