Unfolding uvw on animation

[NanoE]

Got this problem: I've modeled a spherical planet Earth, that unfolds into a rectangular plane. As you can expect, if I use the usual UVW mapping generation tools (spherical, planar, etc...), textures get all messed up during animation. I've tried unwrapping or unfolding the uvw coordinates, but at some point textures start to horribly deform. The whole point is unfolding a sphere into a plane without messing up the texture maps.

Thanks in advance

Pd: I'm using 3ds max 9