If you have a list of order IDs and associated tracking numbers, you can
$shipment_collection = Mage::getResourceModel('sales/order_shipment_collection');
$shipment_collection->addAttributeToFilter('order_id', $order_id);
Then you can go through all the deliveries and add tracking, for example,
foreach($shipment_collection as $sc) {
$shipment = Mage::getModel('sales/order_shipment');
$shipment->load($sc->getId());
if($shipment->getId() != '') {
$track = Mage::getModel('sales/order_shipment_track')
->setShipment($shipment)
->setData('title', 'ShippingMethodName')
->setData('number', $track_no)
->setData('carrier_code', 'ShippingCarrierCode')
->setData('order_id', $shipment->getData('order_id'))
->save();
}
}
.