It seemed like an interesting challenge so I decided to have a go at solving your request.
Here you go: https://dl.dropbox.com/u/14522925/SpriteDrawing.capx
It's not perfect - the captured image seems to be offset for some reason but it's late and I don't have the energy for bug hunting :P
Still, it should get you off to a good start. Should be simple enough to figure out but let me know if you're confused about anything. It basically uses canvas snapshot but first sets up the scene to capture just a small area (the working area). Just FYI, the wait 0 seconds seems to be required, otherwise the capturing doesn't work properly.