you need a compositing programm like combustion or aftereffects or something. secondly in case the camera is moving you´d want to motion track (combustion) the movement and import it to maya as a camera. don´t ask me how to do that. save the animation and export it to any compositing software and "melt" it with your real film.
can´t tell any further details cause I never did such work. hope it did get you in the right direction though.
everything starts and ends in the right place at the right time.