I'm a complete novice at maya but i'm struggling along fairly well up until now. I've created a schoolbus in 3D and rigged it and now i want to animate it into a 2D background which i've made in photoshop. I though i could do this by using this BG as an imageplane but the only way i can get the camera in the BG and Maya's camera to have the same horizon and vanishing point, is by offsetting the imageplane. This way part of my 2D BG and my final animation would be offscreen.
Have you tried rendering your animation as a Maya IFF sequence and then importing the sequencing and compositing with your background in After Effects?
I'm not sure if this is something you've already tried or if you absolutely have to have do all the compositing within Maya. The only other thing I could think of is applying your 2D image to a plane and setting that up in Z space as a type of backdrop.