How can I create animation in SW2006 in an assembly by editing a sub-assembly to move parts of it?

i.e. I have an assembly that has a sub-assembly in a certain position, then for the next key frame, I edit the sub-assembly to have some parts moved or rotated, but the animation will show the assembly with the sub-assembly in the last position, so no movement or rotation.

Basically, the animation is of the sub-assembly but the view is of the main assembly.