Use Morph Manager 4 to create a morphless figure
"Load File" => in the "File of type" window choose "Pose Files" => load an empty pose (or any pose, it does not matter)
Click again the top left button and load your figure
Now the 3rd top left button says "More Options"
Choose "Delete all morph targets from file"
Save under a new name

Use morph injection technology to import only one useful morph
If your figure has no injection channel, you can edit one by hand or use MM4 or use one of several free python scripts to add some to your morphless figure.
You can use Stalle's Poser Little Helper to create injectors from your custom morph

Desactivate shadows untill the final render

Render each character in position. Remove the background in photoshop. Use each render as a texture on a primitive square. Rearrange the squares in  the scene.

Hope it helps