This talks about a counter after immigration, much after check-in counter.
Where can I get an export certificate of customs in India?
Indian Customs counter at airports in India are typically after Check-In & Immigration counters, How / where can I get Export Certificates for them?
Another part of the question I've posted here:
Customs Duty & Regulations specific to the 'Category of items'
Traveling with these Items & Packing:
Items have to be checked-in due to size/ weight & with protective padding in luggage/ suitcase.
Can I bring my desktop computer as check-in baggage on a flight?
Taking a Desktop Computer Overseas - Options?
This talks about packed items in Checked baggage when Importing but not when exporting in Checked Baggage Packed Items at Indian Customs