Fl510 and Lt...
I also brought my hours from flying a 1900 and 200 for a SA operator to the Uk when I did the JAA licence, and the hours were counted towards the Multi Pilot hours required for the ATPL and the MCC.
Lt, for my MCC I just downloaded the page from the SA CAA Part 121 where it states 2 pilots are required and before I left the company I worked for I took photocopies of their AOC which had all the registrations of the planes which were operated under Part 121.
I also had a letter on their headed paper stating that the contracts for the UN and oil companies required 2 pilots for their insurance too.
FL510, if you read LASORS, UK CAA regs, it says hours flown on a Part 23 or 25 type can be used towards the mutli pilots hours required for the granting of an ATPL.
(b1900d is certified under Part 23)