do you mean this bit here?

define('DIR_WS_ADMIN', preg_replace('#^' . str_replace('-', '\-', $p1) . '#', '', dirname($_SERVER['SCRIPT_NAME'])) . '/');
define('DIR_WS_CATALOG', '/');
define('DIR_WS_HTTPS_ADMIN', preg_replace('#^' . str_replace('-', '\-', $p2) . '#', '', dirname($_SERVER['SCRIPT_NAME'])) . '/');
define('DIR_WS_HTTPS_CATALOG', '/');

If so, I have no idea where I am supposed to enter my "admin" as this is a totally different setup to 1.3.9h.

I'm going to bed now, it's late here in NZ so I'll try again tomorrow evening.