If you're looking for historical Civil War content in the forthcoming movie The Last Samurai, I'm not sure you'll find any. If this is the shooting script, the Civil War dies out after page 11.
There is actually a book called The Last Samurai about the fellow who would have been the boss of Tom Cruise's character. It has nothing to do with the film and I myself don't know of any ex-ACW veterans who went to Japan to become "the last samurai" or to work for the "last samurai."
The best known expatriate of that era was, of course, the tempermental Rebel general William Wing Loring who was employed by the Khedive of Egypt. He has a website devoted to his Egyptian generalcy. His memoirs of that service are public domain - Hollywood would suffer no cost in optioning them.
An unreconstructed Confederate, he fought a black Christian Empire for his white Muslim overlords.
Fresh as today's headlines? A contemporary theme in historical spectacle? Yes. And nothing to prevent Hollywood from having Gatling guns chop down loads of miltary extras in the last scene.
We would get a Loring pic and Hollywood would get the umpteenth Gatling gun ending, in slow motion ... can we shake on that?