You could intercept the titles and change them in the USPS module ...

Find where the final output is used and change it to what you want it to read ... example:
Code:
echo 'USPS $type: ' . $type . ' $cost: ' . $cost . ' $title: ' . $title . '<br /><br />';
if ($type == 'PARCEL') {
$title = 'FRED';
}
          $methods[] = array('id' => $type,
                             'title' => $title,
                             'cost' => ($cost * $shipping_num_boxes) + (MODULE_SHIPPING_USPS_HANDLING_METHOD == 'Box' ? $usps_handling_fee * $shipping_num_boxes : $usps_handling_fee) );