Appendix 2 to JAR-FCL 1.055 "16 The theoretical knowledge instruction shall be conducted by an authorised instructor holding the appropriate type/class rating or any instructor having appropriate experience in aviation and knowledge of the aircraft concerned, e.g. flight engineer, maintenance engineer, flight operations officer."
It will be up to the individual TRTO to decide what requirements it wishes to set for its TKIs and for the approving Authority to decide if the Company's requirements acceptable for approval.