You could think about approaching it like braille? Have a tablet with lots of buttons arranged like a checkered sheet of paper. Each dot/square can be pushed in to form a letter or word and the sheet it iscan be easily reset by pushing all the buttons back out again.
They could have a tool specifically designed for the purpose of pushing these buttons, with each finger (or whatever they have) controlling one of the mechanisms in the tool, which push in the buttons. Obviously this works best with a language that does not have a tonne of different letters
