there is well done tuto on the foundry website, i suggest you check them as they will be more clear than anything else.
but basicaly you need to project on a card using a non animated camera based on the frame you want. then the card plug into a scene node where other things can be plugged, then a scanline node with the scene in obj and the fully animated cam in cam. i would not plug any bg in the scanline and use a merge to plug the b (you may need a rezise on your scanline bg if you use a weird cutom format)
you should see your projection
cheers