[imexhouse]

I've compared the init.php from 4.1.8 to config.php from 4.0.19, and most of init.php is incorporated into the 4.0.x. config.php
There's a line in 4.0.19 auth.php:

include_once $xcart_dir."/config.php";

I'll try to plug your code around that line and see what happens.