Here's a quick hack which allows for new support tickets to be pre-populated from get variables - very handy if you want to pre-fill email address, phone number, etc...
in /include/client/open.inc.php , just add this 1 line on line 4 (after $info=($_POST && $errors...)
//If there are get variables, but post is blank, use GET variables instead
$info = ($_GET && !$_POST) ? $_GET : $info;
That's it! Now you can prepopulate the fields when creating a new ticket using get variables, i.e.
Hope this helps!