I had a blind client until he moved out of state.  I would just go line by line through his return (pretty easy, 1040+Sch A) and then read the jurat on the 8879.  I would put the ball point of the pen on the signature line and he was pretty good about signing straight across (a couple years were a little crooked but these things just go in my file anyway).  Don't know what the right answer is, but it got the job done.