Using 3d rotoscoping to animate characters

Like in http://www.youtube.com/watch?v=qm6UIclnbdM
Is there any tutorial on how to do this? Is this possible with using blender only, or do I need some external software to track movement?
Thanks.

The motion tracking is the least of your worries:http://www.youtube.com/watch?v=w3E3zRQSpcI
The problem is when he says ‘extrude it’ I got stumped(I’ve tried this before)

-Thanks

Thanks for the reply, the video was helpful. I also do not understand how did they do this “extruding”, maybe someone can shed some light on this?