What you need to do is use camera tracking software ie Boujou to track the camera movement in the real life footage.You can then load the data gathered into a Maya camera to match the movement and of course you need to also match the film back, aspect ratio, Speed (FPS) and lens used.
you need to match the lighting and shadow direction and softness ect with Maya lights to create shadows for your object9 i would render the shadows in a seperate pass.Also you will need to create some geometry to cast any shadows on your animated object if needed ( for example a character that might walk over a shadow on the ground of the real footage so that shadow needs to be cast on your animated object too).
Load the live footage onto the shot camera image plane turning down the alpha gain to get some transparency to enable you match any geometry you need to create.
Create any standin geometry needed to obscure your Maya character if it needs to go behind anything in the real footage, you can put a black hole shader on those objects then render out your animation using the tracked camera data and don't forget to save the render in a format that includes an Alpha channel.Finally you can then take your animated Char into a compositing app like After Effects, Shake or Combustion ect and composite the two together.

I bet you wished you never asked now ..lol