1- simple 2 lines letter addressed to the head of traffic department, signed and stamped by the sponsor, stating "please note that Mr.X holding ID No.# expiring on (date) is working under our sponsorship and we don't have any objection to issue light / heavy driving license to him"
2- attach the application form (which is available in MOI site and has to be signed and stamped by the sponsor)
3- copy of your company computer ID / CR / authorized signatory ID