Hey Bob,
If you are using PHP5 you can use SimpleXML. It's by far one of the
best objects that PHP introduced into PHP5. It comes as a standard
package so no need to install anything different.
Now, assuming you could follow the ideas on the "Extras" page on the
website you could then get the output into $strPage. From there you
could do the following so you can see the structure.
<?php
$xml_load = simplexml_load_string($strPage);
echo "<pre>";
print_r($xml_load);
echo "</pre>";
?>
You will then see the XML structure for SEOMoz and any other service
that we offer for that matter.
Take care and good question!
Chad