Kt, I'm also interested in developing my teacher training skills. I currently work as a trainer, but I would like to do more online work. So, any websites about that would aslo be appreciated!
In answer to your question, why not check out the Boland school website? They do a month long teacher trainer programme, with the option to then become a trainer in one of their schools. The only problem with this is that it is a fairly expensive course. On first inspecition, it does look rather like a glorified TEFL certificate, but maybe thats was just my impression. Good luck!!