JAR OPS 1.365 has the answers - a bit too long to post but here's some of it:
JAR–FCL 1.365 TRI(MPA) – Requirements
(See Appendix 1 to JAR-FCL 1.365)
(See AMC FCL 1.365)
(a) An applicant for the initial issue of a TRI(MPA) rating shall have:
(1) successfully completed an approved TRI course at an approved FTO or TRTO (see Appendix 1 to JAR-FCL 1.365 and AMC FCL 1.365);
(2) completed at least 1500 hours flight time as a pilot of multi-pilot aeroplanes;
(3) completed within the 12 months preceding the application at least 30 route sectors, to include take-offs and landings as pilot-in-command or co-pilot on the applicable aeroplane type, or a similar type as agreed by the Authority, of which not more than 15 sectors may be completed in a flight simulator; and
(4) conducted on a complete type rating course at least 3 hours of flight instruction related to the duties of a TRI on the applicable type of aeroplane and/or flight simulator under the supervision and to the satisfaction of a TRI notified by the Authority for this purpose.
[The requirements above are fulfilled if the applicant hold a JAR-FCL licence, have been issued a specific authorisation in accordance with Appendix 1 to JAR-FCL 1.300 and complies with JAR-FCL 1.370.]
(b) Before the privileges are extended to further MPA types, the holder shall have:
(1) completed, within the 12 months preceding the application, at least 15 route sectors, to include take-offs and landings as pilot-in-command or co-pilot on the applicable aeroplane type, or a similar type as agreed by the Authority, of which not more than 7 sectors may be completed in a flight simulator;
(2) satisfactorily completed the relevant technical training content of an approved TRI course at an approved FTO or TRTO (see AMC FCL 1.365); and
(3) conducted on a complete type rating course at least 3 hours of flight instruction related to the duties of a TRI(MPA) on the applicable type of aeroplane and/or flight simulator under the supervision and to the satisfaction of a TRI(A) notified by the Authority for this purpose.
etc etc .............................