Inverse Kinematics for more complex pose

Hi,

I have started learning Mecanim and IK system (based on Mecanim sample) in unity and I reached my first problem. While making character look at something and aim using one hand is basic stuff I did not know how to handle a little bit more complex aiming.

This is my idle aim animation (I want to achieve this effect while aiming):

And using approach I did for single hand I ended up with something like this (values for position and rotation weights were messed up but I hope you see the problem):

I also tried setting effector on left hand and made right hand tied to it but it also did not work properly. How should I attempt to solve it? And if you have some good IK tutorial I would be greatfull for sharing.

EDIT1:

Ok so I read about animation layers and I can make layer for hands and body - so Is there a way to make entire layer use function LookAt (just like it works for the head)?