We have a user who is legally blind and we use a software called JAWS so that she can communicate with her PC. Once the windows signon box is up on first boot the PC will talk to the user and she can login or whatever she needs by speaking.
Is there a way to make safeboot allow this user to login by using a similar method?
Have you looked into a two-factor method? I would hope that she doesn't speak her username and password every time she logs in. Even if she is blind, can't she feel the keyboard layout and type like everyone else? It might be helpful for the computer to speak the name/description of the field the cursor is in.
Another cheat would be for her to login to a Citrix-like client, so encryption would not be necessary, since there is no actual data on the device.