Altering geometry of a skinned mesh.

[mlp1802]

I need to change geometry of a skinned mesh, dynamically, so the player can customize the character (make arms/leg/body longer, shorter, thicker etc).
I know that you can access these data in the Mesh struct, but as far as I know, only if you have the index of each specific joint.
Or is there some other way to achieve the desired functionality?