I have little use of my hands and can only type with one finger. For many years, I've been using many versions of voice systems to dictate my work in writing novels and short stories.
For anyone with any kind of typing disability, I would highly recommend one of the voice systems like Dragon NaturallySpeaking. It takes a while to get used to this form of communicating, so a person needs to be patient, persistent and maybe some tutoring our guidance so they don't give up before they start accomplishing.
One area that is still difficult is operating the computer and mouse for those that do not have hand dexterity to operate touchscreens and other aids that do not work for some of us.