A couple guys have done this already. One use a mini-keg and the other used an oil bag. The latter might be a vendor.
Consolidating my posts:
Here's a third one, Larkfarms, although he doesn't have really good photos of it online:
http://www.bonnevilleamerica.com/photopo...=500&page=1
Here's the oilbag style one:
http://www.bonnevilleamerica.com/photopo...ium&cat=500
I don't have time to look for the other one right now.
