just did 2 this week, and up until now its just a matter of patience, i did try something new this week and it worked 'pretty good' i mounted a router on my tool rest and slowly turned the antler by hand and edged the router in with every rotation, needs a lot of fine tuning but i rounded 5 blanks in the time it took be to turn 1 the normal way.
disclaimer:i am a trained professional, don't try this at home,
Treat it just like any other blank, cut it to length, drill it for your tube, glue the tube, square the ends, turn to size. Be ready for the smell!
Here is a good place to start to get it drilled easily.... Drill2 - YouTube
I wasted a few before I did it this way.