[6impy]

Well, actually I didn't get it working so it would use the same session. I decided I wasn't going to deal with the forums custom sessions and just create my own when the user used the non-forum part of the site.

What I have to do is the following on my header file:
if ($HTTP_COOKIE_VARS['bbuserid'] and $HTTP_COOKIE_VARS['bbpassword']) {

session_start();

if (!session_is_registered("userid")){
Header("Location: /pages/session.php?url=" . urlencode($_SERVER[REQUEST_URI]) . "");
}
}

So, basically, this code checks for the cookie vars, and if they exist it runs "session_start();", if the session variable userid has NOT been registered, it refreshes to session.php to register the necessary variables and then immediately refreshes back (hence including url = urlencode($_SERVER[REQUEST_URI]) in the location).

Then in the session file:

session_start();

$db->changeDatabase("forum");

if ($HTTP_COOKIE_VARS['bbuserid'] and $HTTP_COOKIE_VARS['bbpassword']) {

if (!session_is_registered("userid")) {

$bbuserid = $HTTP_COOKIE_VARS['bbuserid'];
$bbpassword = $HTTP_COOKIE_VARS['bbpassword'];

$userid = "";
$result = $db->query("select userid,username,usergroupid from user where userid='$bbuserid' and password='$bbpassword'");
$row = $result->fetchRow($mode);
$userid = $row->userid;
$username = $row->username;
$usergroupid = $row->usergroupid;

if ($userid) {
session_register("userid");
session_register("username");
session_register("usergroupid");
}
}

}
}

Header("Location: " . $url. "");

}

This is just the initial code, it needs some work....