Stone lifting has been a life changing thing for me. It got me through a really difficult time in my life, helping me restore my mental and physical health. I’m surprised to see it on Hacker News.
How does one get into this sport? There are no historic stones near me, in SoCal, and I'm not really able to get to a powerlifting or strongman gym, that night have stones, due to my professional and personal life / obligations. I mostly lift out of a garage gym but I'm fascinated to keep seeing this sentiment over and over again as I've pushed more into sandbag training.
edit/ Sean has some detailed information on the site about his training.
Sandbag training at home is great, and of course you can go to a landscaping store or just in the middle of nowhere and find a big rock or two to bring home. I have a 320lb landscaping rock in my back yard! Regular barbell training- especially front squats and deadlifts will translate to stone lifting well.
I personally train mostly at home, and have an online coach I send videos to for feedback. I then only occasionally travel to a strongman gym, because it is far away. Maybe once or twice a month.
The book Stonelifting by Martin Jancsics and Dr. Bill Crawford is also excellent and can be used to build your own program at home.