Yes, I trim my own horses. And all my client's horses. I am a part time barefoot trimmer. I started in 2005 when we transitioned our horses to barefoot. I learned by telling the farrier we had at the time that I wanted to learn. Then we moved, I went to sea (Navy) and my wife got us a barefoot trimmer to do the horses. When I was in port, I would work with the trimmer to learn more. Eventually, I took over ours without any outside assistance. Then I started taking clients.
As for learning, I recommend you start with a barefoot specialist in your area. All the ones I have met that are any good will be happy to teach you how to do it yourself.
I highly recommend Equine Sciences Academy. I am enrolled in the Hoof Certification program, because, while I have clients, I can always learn more. There are a lot of flexible options for how to pay for the courses and the material is definitely worth the cost.
Alsea1 - post some pics. Based on what you said, the flare may be needed by the hoof to stabilize/compensate for the previous injury. However, it could be something completely different.