Mecanim animation

I am using Mecanim in Unity 4.2.2f1. I have one animation clip for running forward. I want to make running backward also using this clip by setting it's speed to -1 (it looks ok).

To make perfect transition between these clips I need to fulfil the following: if at the moment of transition we have the normalized time of running forward clip equal to n (n lies in 0..1 range) then we must transit to normalized time of running backward clip equal to 1 - n (and vice versa).

Can I somehow realize this scenario by means of Unity Editor or is the only way to do it is setting normalized time from script?

P.S. I've tried to implement this using Animator.ForceStateNormalizedTime(), but it causes sudden flickering of the character (while pose is ok) - it looks like a one-frame lag. No matter where to place this function: in Update, FixedUpdate or LateUpdate there's always this flickering for a second.