You'll have to read the info on the sites. I know that atleast for BHS, they have some online study materials, although you may have to pay for them, I don't know for sure. Documented teaching time is most likely required, possibly along with videos of you teaching/riding, along with the required in-person testing. If you can't find a centre near you, you may have to be willing to travel.
I will look and see what they have :)