We just need to add 3 columns to the Sales->Invoices (Listing & Export) in the administration backend.
These 3 columns are: Carrier | Shipping | Shipping Country
#Carrier -> should be something like: DHL, UPS, Fedex, etc.
#Shipping -> its the tracking number
#shipping-country -> the shipping country
We already add the collumns to the grid just need to get the data on.
Check the attachment for the details.