http://www.rcgroups.com/forums/showpost.php?p=34763753&postcount=28152

REMEMBER: if you screw some of these settings, the copter will violently start to oscillate. If you do first test with props on at hand, grip the copter VERY well.

enter following cli command:

set yaw_motor_direction = -1

also you might need to apply this command:

rxrange 2 2000 1000

.. depending if your yaw direction is wrong. When I had stick arming, I had to enter this to get stick arming to left corner and still get yaw to work in correct directions.

(and ofcourse, reverse your motor rotation direction at ESC and “mirror” your prop rotation direction)