Changing vertex groups weight?

Is it possible to change the weight of a vertex group to a bone in the scene?

Example:
A hollow 1cm cube with a thickness of 1mm. I would like to make the cube 2cm but keep the thickness 1mm through the whole animation.
I think this could be done by having the interior vertex group be weighted to the bone as a function of the bone's scale.

In Blender, stacking the armature before the solidify modifier achieves this, but the solidify modifier is applied during B4W export.

If there's a better to way to maintain even thickness, I'd be open to that, as well.

I made a video showing the process
Just don't forget to bake your animation before export :)

samethick.blend
samethick.html

That is helpful! Thank you!

For more complex shapes meshes I can see how it could it very messy, though.

It can be done using shape keys or vertex animation then :)