If you want to do it to a non-animated mesh, couldn't you simply do this:
rotatemesh m,0,45,0
scalemesh m,2,1,1
(I assume you are asking how to make a mesh twice as wide in the world's x-axis after first rotating the mesh by 45 degrees about the y-axis)
rotatemesh m,0,45,0
scalemesh m,2,1,1
(I assume you are asking how to make a mesh twice as wide in the world's x-axis after first rotating the mesh by 45 degrees about the y-axis)