BlxTennis, this youtube link shows a method to pull two main strings at the same time which avoids pulling strings over the frame on the throat end. It also results in more consistent tension (avoids the friction loss of pulling tension over the frame) and also eliminates the crank arm interference with the racquet handle.
This link has been posted several times, but I don't think anyone has tried it. Not sure why because the technique works good with crank machines.
http://www.youtube.com/watch?v=JHaUrtUqS_M