I am really interested in this idea ....I am training to be a teaching and so you touched a nerve!! This won't directly help you but I think you have opened a can of worms...
I use a site
www.touchtyping.com that is brilliant...So in theory all you need is an adapted key board and for the Font on screen to be user compatible ...
I only found one place in Bath that offers course!!!
I have emailed this idea onto my daughter and my husband who are graphic designers, web builders ( generally techie people)
I am also going to write to admin@goodtyping and see what they can come up with....could you mail them too
This is my first time answering someone on Nappey Valley and I am not sure I should leave my details as I think this goes public...
Good luck with this .. You should be able to get this for free and online..it may be worth emailing some schools who specialise!!!