Make a plguin for postdata_presave and threadfpdata_presave
And add the following code to both:
PHP Code:
global $vbulletin;
$pagetext =& $this->fetch_field('pagetext', 'post');
if (stristr($pagetext,'https://twitter.com/')) {
$string = $pagetext;
$pattern = '#https?://twitter\.com/(?:\#!/)?(\w+)/status(es)?/(\d+)#';
$replacement = '[tweet]$3[/tweet]';
$pagetext = preg_replace($pattern, $replacement, $string);
}
Won't gurantee anything, but it does indeed convert a twitter link to the format you want.
See:
http://elite-source.com/testthis.php