Same setup as any other carrier service. Only difference, in Admin > Shipping Service, create the service, with override ticked.
1. Create a Service, Admin > Shipping > Service
Override must be ticked
A service with override selected will not be available on Ecom site to customers, only available via Telesales.
2. Create Service Charge record
Admin > Shipping > Delivery Charges
( will need one record per country to be serviced )
3. Create record in Admin > Shipping > Carrier Assignment Rules