I'm about to have a custom LC jacket delivered next week, but really it was just to get a LC jacket with a more Screen accurate back length (on me), in other words better fit. I did ask them to put LC hero pockets on it though, be interesting to see if they've done that.
There are a couple of fans who have done what you're asking, over on fortune & glory. I believe one of them posted a thread with the specs he asked for. Although I think he misfired on a couple of things.
The basic things you would want to ask for in the custom box are, no facings on the zip. No double stitching on the arms. You would also want to ask for Hero collar and Hero pockets. D-rings and no x-box stitch (these last two options are already preselected in the drop down box). When I enquired about this a while ago they said it would be doable but I'd have to sign something agreeing that the jacket would be non returnable.
As for the skin. I believe Peter Botwright said the movie jacket was a thick veg tanned lambskin. As you've noted though, the distressing is key to getting the screen accurate look. Plenty of pictures to copy from though.
Also drones33 noted above, Westeds current batch of predistressed hide looks very good on a last crusade, and you can still add the extra screen accurate distressing on top.