It's great to see someone so enthused about chair yoga! It's not very "*", but the students really benefit from it and there are too few professionals putting time into it.
Liz and I are trying to change that, and we're making some progress, I'm happy to say.
We periodically conduct chair yoga teacher training. We have received a generous grant from the Multiple Sclerosis Foundation that will sponsor 10 yoga teachers to be trained to teach Yoga In Chairs to people with MS. There is no cost to the teacher for the training itself!
In-person training is the best way to transfer knowledge, but we have developed an at-home training program that is affordable yet comprehensive. (The program is for yogis and yoginis that already know how to teach yoga.)
Finally, you might consider purchasing and studying chair yoga videos, which there a few of.
I've started a chair yoga blog which should have some items of interest to you. Paul Jerard has several articles about chair yoga in his blog at http://yoga-teacher-training.blogspot.com/
If you have any particular questions about chair yoga, we'd be happy to help you out!