You should be able to do this in your video editor more easily than in Poser. It might require a video editor with multiple tracks in a timeline. Render out a Poser animation of your moving figure (I assume you're animating) either as a series of stills (making it easier to isolate the figure in your video editor via the alpha channel) or as a movie (you can knock out the background in your video editor using a color key matched to the Poser background). Then resize the Poser movie in your video editor to fit the background movie, which you would presumably have on a lower track in your video editor timeline. If you want the figure to slowly "appear" in your video, just keyframe the transparency of the Poser movie clip to your taste. If you want it to transition slowly from an outline figure to a full, non-transparent figure, you may have the appropriate filter in your video editor if it is good enough (Final Cut Pro or Avid Express). Alternatively, render out your Poser movie twice: once with a toon outline, and once without, then overlap the two movies as separate timeline tracks in your video editor (the background movie on a third, bottow track), and keyframe the transparency of each Poser clip (or you could use a cross-dissolve transition with both clips in the same track) to your need until you get the transition effect you want.