Various points to make...

• as mirod says, that's an ugly piece of XML. But that's not the problem we're here to solve today...
• getElementsByTagName works only on a Document object, not on any element: it finds all the elements with the given name anywhere in the document. I don't think that's what you need.
• to do the match, you could use getAttribute() to get the value of the use attribute, and then use a regexp or something similar to test if it contains the value passed from the command line. Like:

  $attrValue =~ /\Q$param\E/
  [download]

  where the \Q...\E is to avoid strange characters from being interpreted by the regexp engine.
• learn XPath. Really do. That whole program can be reduced to a single XPath query. And it would be easier to read.

-- 
        dakkar - Mobilis in mobile