Try inserting this into main.inc.php:
// ---------------------------
// Convert ssl markup -> html
$Body = eregi_replace("\[ssl\]www([^\[]*)\[/ssl\]","<a href="https://\\1" target="_new">https://\\1</a>",$Body);
$Body = eregi_replace("\[ssl\]([^\[]*)\[/ssl\]","<a href="\\1" target="_new">\\1</a>",$Body);
$Body = preg_replace("/\[ssl=https:\/\/(.*)\]([^\[]*)\[\/ssl\]/","<a href="https://\\1" target="_new">\\2</a>",$Body);
$Body = preg_replace("/\[ssl=(.*)\]([^\[]*)\[\/ssl\]/","<a href="https://\\1" target="_new">\\2</a>",$Body);
// ---------------------------
// Convert ssl markup -> html
$Body = preg_replace("/<a href="https:\/\/(.*?)" target="_new">(.*?)<\/a>/","[ssl=\\1]\\2[/ssl]",$Body);
Then just use "ssl" instead of "url" for secure links . [ssl=https://...] and so on...
This is untested.
Mateo Byler
CruceDeCaminos.com