It seems heinemann's usage is not correct and does not achieve the intended result.
This method's purpose is to change a global <xsl:param> value in the XSL stylesheet--not to change an attribute of any other element. <xsl:param> basically lets you set up a stylesheet which can be customized (as from PHP) externally (without needing to tamper with the original XSL file).
Here's an example of usage (that will work):
Stylesheet:
<?xml version="1.0"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:param name="print_something" select="defaultstring"/>
<xsl:template match="/mydoc">
<p style="color:red;">Printed parameter: <xsl:value-of select="$print_something"/></p>
</xsl:template>
</xsl:stylesheet>
Script:
<?php
$dom = new DOMDocument();
$xsl = new XSLTProcessor;
$xsl->setParameter( '', 'print_something', "Now I've overridden the default!");
$style = realpath( "./my_stylesheet.xslt" );
$dom->load($style);
$xsl->importStyleSheet($dom);
$dom->loadXML('<mydoc></mydoc>');
$out = $xsl->transformToXML( $dom );
var_dump( '<pre>',
htmlentities( $out, ENT_QUOTES, 'utf-8' ),
$xsl->getParameter('', 'print_something'),
'</pre>' );
?>
gives:
string(5) "
"
string(143) "<?xml version="1.0"?>
<p style="color:red;">Printed parameter: Now I've overridden the default!</p>
"
string(32) "Now I've overridden the default!"
string(6) "
"
Notice that at present adding a namespace will not work. The only option at present is to set the first parameter for namespace to an empty string (though you can add the prefix with colon to the second argument for name in order to set the parameter for a namespace-prefixed parameter name).
See http://bugs.php.net/bug.php?id=30622