I've used a system like this before:
http://beerloons.wordpress.com/2009/...ni-keg-system/
Was never really pleased with the CO2 cartridges and over time, the metal kegs got all banged up and unusable. I think I still have the tap handle somewhere, you're welcome to it if you go this route. It *did* save considerably on bottling time.
Can't wait to do my chest freezer conversion!