Actually... it is possible. Sort of. 😉
This is what I discovered in my quest for playing Blu-Ray on a Mac:
1. Download and install 'MakeMKV' from here:
http://www.makemkv.com/download/ (this is currently a 60-day free beta demo)
2. Pop your Blu-ray DVD into your external Blu-ray drive (I use the LGBE06).
3. Open 'MakeMKV' and click on the button that opens the Blu-ray disc.
4. Once your Blu-ray disc is read, select the file(s) you want - the actual movie will most likely be the largest file - set an output location, then click 'Make MKV'.
5. Download and install the latest free version of 'Plex' from here (I love 'Plex'!):
http://www.plexapp.com/plexstable.shtml
6. Right-click the .mkv file and select 'Open With - Plex'.
So far, that works really good for me. I hope it does the job for you too (for now, at least). All the best! 🙂