Product review (5 stars): Only needed a screwdriver
Does the job, although I don't know how long theyll last since I just installed a pair.  I found it easiest to hook the cable ends on the door tabs first, then hook the two springs to one of the cable ends, and finally hook the springs to the other cable.  The last step requires pulling the springs so they have some resting tension, but I was able to do this fairly easily using just my hands.  The only tool I needed for the repair was a screwdriver to remove the panel screws.