off the top of my head, on yours sb, setup a page in your password protected area, then have a phpinclude include the file utilizing a user/password to access the member area:
<?php include("http://user:pass@www.yoursite.tld/protected/file.php"); ?>
By using a php include the password shouldn't be shown to the user, unless there is a password issue (like it being wrong). This is ofcoarse assuming you're using .htpasswd for your protected area.