$xsl: should be an xsl content buffer
$result : will be the result ;-)
$xh = xslt_create();
$arguments = array('/_xml' => $xml, '/_xsl' => $xsl);
$params = array(
//~ 'param1' => "hello world",
);
$result = xslt_process($xh, 'arg:/_xml', 'arg:/_xsl', NULL, $arguments,$params);
xslt_free($xh);