Bug found (marked red)
<file name="$boarddir/index.php">
<operation>
<search position="before"><![CDATA[
require_once($sourcedir . '/QueryString.php');
require_once($sourcedir . '/Subs.php');]]></search>
<add><![CDATA[
require_once($sourcedir . '/Subs-Seo4SMF.php');]]></add>
</operation>
<operation>
<search position="before"><![CDATA[
// Fall through to the board index then...
require_once($sourcedir . '/BoardIndex.php');
<add><![CDATA[
header("HTTP/1.0 404 Not Found");]]></add>
</operation>
<operation>
<search position="before"><![CDATA[
'.xml' => array('News.php', 'ShowXmlFeed'),
]]></search>
<add><![CDATA[
'seo4smfadmin' => array('Seo4SMFAdmin.php', 'Seo4SMFAdmin'),
'seo4smfadminsave' => array('Seo4SMFAdmin.php', 'Seo4SMFAdminSave'),
'seo4smfadminsavexml' => array('Seo4SMFAdmin.php', 'Seo4SMFAdminSaveXML'),
'seo4smfsitemaps' => array('Seo4SMFSitemaps.php', 'Seo4SMFSitemaps'),
]]></add>
</operation>
</file>
In the current version the 404-part didn't get into index.php.
Regards, Christian