question about global.php

[ben_freefly]

I'm a newbie to vBulletin, and I'm trying my hand at integrating it with a client site that uses osCommerce. In a nutshell, I want to automate creation of forums, users and permissions based on products available and customers that have purchased the products. I have been successful in some of what I'm trying to do, but I have a question about the inclusion of global.php. I have a single PHP file with all of my functions that access the forums and at the start of the file I have

chdir('/path/to/my/forums');
require_once('/path/to/my/forums/global.php');

Everything else in the file works, for the most part, with that include as long as I have already logged-in to the forums through the normal login method. If I'm not logged-in, however, accessing any one of my custom functions results in the page redirecting to the forum login form. Is there any way to include global.php without needing to login to the forums?