Actually the FS modding forum gets much more traffic than Inferno's subforum, and this is exclusively something that belongs in FS modding. To answer your question, you'll need to add turret entries to ships.tbl for your new hecate, but doing so is just a simple matter of copying one turret declaration, adding it to the end of the list, and just changing the name so that it references the correct turret number. Pretty simple really. And you should probably go through and arm it based on where the turrets are; I highly doubt that the turrets on the Mk. II are in positions similar enough on the original for them to deserve the same function.
Oh, and if an admin sees this and has the chance, could you move this thread to FS modding where it belongs?