lagrangian formalism - The Euler-Lagrange equations for rigid body rotation

The equations of motion for rigid body rotation are:

$I\,\dot{\vec{\omega}}+\vec{\omega}\times I\,\vec{\omega}=\vec{\tau}$

How i can calculate this equations using Lagrangian method ?

If i use $L=\frac{1}{2}\vec{\omega}^T\,I\,\vec{\omega}$

i don't get the right equations.