Attached Link: http://market.renderosity.com/mod/forumpro/showthread.php?thread_id=996262

Have a look at this as well. This isn't quite traditional multi-pass rendering, but is also a really useful tutorial using multi-pass rendering on Carrara's lights rather than the model textures. It's what I use to keep render times & proccessing/memory usage down. Once you've set your lighting images up in Photoshop you can still use the G-Buffer information to control depth of field etc.