using digital characters

I would like to do stop motion using digital characters such as this little 3D person: http://images.freepicturesweb.com/img1/01/02/6.jpg
Now that iStop Motion has a screencast mode, this seems possible.
What I want to do is pose the character (requires a 3D environment), take a screen snap and so on until I have enough frames to do a short video. Tweening would make this process infinitely easier.
Can I get to this point using iStop Motion today?

Forgot to mention that doing this in front of a virtual green screen or having an alpha channel would also be important.

Tweening is not built into iStopMotion as it causes strange distortion in most cases. But other than that it is possible. You want to make sure you have the background of what you capture to be green so it gets captured into the iStopMotion document.