did you ever find a answer?
i'm doing this exact same thing right now. I'm updating a 3.8 product that used that same tutorial you mentioned to do an auto template edit.
I've updated my code this far
Code:
if ($forumid!=$vbulletin->options['mrt_id']) {
$original = '<li><label><input type=\"radio\" name=\"do\" value=\"movethread\" tabindex=\"3\" /> {vb:rawphrase move_thread}…</label></li>';
$replace = '<li><label><input type=\"radio\" name=\"do\" value=\"recyclethread\" tabindex=\"3\" /> {vb:rawphrase recycle_thread}…</label></li>';
$vbulletin->templatecache['SHOWTHREAD'] = str_replace($original,$replace . "\r\n\t\t\t" . $original, $vbulletin->templatecache['SHOWTHREAD']);
}
BUT templates are handled differently now. just peeked into several v4 products to see how other people are handling it & it looks like most people are doing their auto template inserts using template hooks. that doesn't help me.
any help would be appreciated working hard trying to retrain myself to vb4 & I'd rather learn how to do it right than just go edit the template.