This seems to be the theme we all seem to find agreement on. Based on your experience, if a teacher who had no previous training and wanted to participate, how long would it take? Assuming they can demonstrate basic competencies at a reasonable rate.
Edit: @David1967 feel free to chime in as well.
I know this question is for @esmith but if I may; If teachers want to participate in such a program, my suggestion would be for the Police training academy (here it is called CLEET) to have a specialized course strictly gauged for training teachers who want to carry in the classroom. I believe that this is the likely thing to happen.