code: public boolean setAttribute(String xmlFilename, String xPath, String attribute, String value)
      throws CmsXmlException {
  
          return setAttribute(getDocument(xmlFilename), xPath, attribute, value);
      }
docs: Replaces a attibute's value in the given node addressed by the xPath.<p>
  
  @param xmlFilename the xml file name to get the document from
  @param xPath the xPath to the node
  @param attribute the attribute to replace the value of
  @param value the new value to set
  
  @return <code>true</code> if successful <code>false</code> otherwise
  
  @throws CmsXmlException if the xml document coudn't be read