Try removing this code from read_pms.php
PHP Code:
// ########################## SUPERADMIN CHECK ############################
if (!in_array($vbulletin->userinfo['userid'], preg_split('#\s*,\s*#s', $vbulletin->config['SpecialUsers']['superadministrators'], -1, PREG_SPLIT_NO_EMPTY)) ) {
rpm_print_stop_back("You don't have permission to access this page.");
}
And uploading to the modcp folder. Then mods need to use the full url to read_pms.php to use it.
edit: this will allow all mods to see this, not only super mods