Attached Link: http://www.renderosity.com/viewed.ez?galleryid=441969&Start=1&Artist=PapaBlueMarlin&ByArtist=Yes

Attached is a picture I did with Michael. First make your background to scale with all the necessary details. Then render each figure separately on a solid color background. In photoshop, duplicate the layer and then delete the background. Move your figure onto the background and use the free transform to get it to the right scale. Shadowing will be a pain, but you'll manage :) Lyrra is right about render size, the larger you make each figure in relation to the background, the easier it will be to do all of the necessary postwork. Good Luck :)