access document object during xform on IE6

During XSLT transformation using IE6 I am trying to access the
document object to extract the URL of the XML doc currently being 
transformed. Since the document object does not exist I am getting
an error. Q1) Is there any way to salvage the approach used below to
somehow access the URL of the XML page being transformed? Q2) If the
document object is unavailable is there any other object that can
be used in its place? Thanks in advance.

<?xml version="1.0"?>

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                xmlns:msxsl="urn:schemas-microsoft-com:xslt"
                xmlns:user="http://mycompany.com/mynamespace"
                version="1.0">

 <msxsl:script language="javascript" implements-prefix="user">
  <![CDATA[
   function DoIt() {
     return   document.location.href;
   }
  ]]> 
 </msxsl:script>
 
 <xsl:template match="/">  
  <xsl:value-of select="user:DoIt()"/>
 </xsl:template>
</xsl:stylesheet>

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