Procedure forregistration under excise by a non manufacturer

ONE OF MY CLIENT IS A TRADER IN GOODS. HE PURCHASES GOODS FROM MANUFACTURER WHO LEVIES EXCISE TO HIM. HE THEN SUPPLIES THE GOODS TO HIS CUSTOMERS WHO ARE ALSO MANUFACTURERS. HIS SUPPLIERS ARE NOW DEMANDING SET OFF OF EXCISE DUTY PAID BY HIM. WHAT IS THE PROCEDURE TO REGISTER SUCH DEALERS.