Blender 3D is a 3D animating software that can be as good as SFM or Miku Miku dance.
But you don`t need Steam to get and it`s 100% free.
Which version of BLENDER is the best?Edit
If you're going to use blender 3D, then use blender 2.65. If you want to import MMD models (or models from miku miku dance), then use the latest version.
How YOU can use itEdit
Import models from any 3D software; if you got the plugins for import models from the software, in the case Miku Miku dance.
If the file you imported is rigged (.dae files mostly but also some others) then you can pose you model into any poseur even animated them by manipulated any of the bones in the armature.