[Antivirus]

you want to set up a plugin to redirect using hook location: register_activate_process most likely.

UNTESTED, but somethign like the following:

PHP Code:

$vbulletin->url = 'yourmessage.php?' . $vbulletin->session->vars['sessionurl'] . 'do=whatever';
eval(print_standard_redirect('redirecting_message'));