I've tried making ales in cornelius kegs, and it works but it's never quite right. Mostly, it's the venting that is difficult. I recommend going whole hog, and picking up a proper cask. This is an investment, but it is worth it!
So, here's the list of what you need:
-a cask. I recommend a 5.4us gal. "pin". A cask goes by many names and they are all based on size. A firkin is a 10.8gal. cask.
-hard and soft spiles
-Keystones and shives
-cask breather-controversial since they are not Camra approved, but who's gonna empty a full cask in 2 days at home?!
-tap-gravity, or threaded to hook up to a beer engine
-stillage-a way to rest your cask so it does not go undisturbed
-a way to keep the cask between 52-58F-cellar temp.
-co2 tank to hook up breather.
-beer engine if you do not want to serve gravity. Remember, all a beer engine is is a tool to get the ale out of the cask. Nothing more!
-cask widge-Highly recommended!!! I love this little device! It makes venting so much cleaner in my chest freezer!
All the above can be found at www.ukbrewing.com
In the picture below is a rubber mallet, shive, keystone, soft spile, cask widge setup, gravity and non tap. I don't use the taps much anymore since I use the Cask Widge mostly. Also, thanks to the cask widge, I don't need hard spiles anymore. Just turn the butterfly valve to close off the cask after venting.
2 casks. These are 5.4US gal "pins". I also have a 10.8US gal "firkin".
Beer Engine-Note, these are fun! They look cool. All your friends will want to play with it! BUT, they really have nothing to do with producing Cask Ale. All they are is a tool to pull the ale out of the cask since there will be no artificial C02 pressure pushing the beer. In fact, most cellarman I've spoken to in the UK prefer beer drawn by gravity, straight from the cask in the cellar. Note short spout and no sparkler.
Here's my other pump that has yet to go into service. I picked it up recently on ebay. It works fine, but isn't in as good of shape as my Angram pump. Still, it pumps water fine, so I'm sure it'll be ok. Good cleaning and it'll be good to go!
When I first started making cask ales I had a really goofy gravity setup in the garage, but hey it worked! Basically, all you need is a way to get the cask just slightly higher than your glass. In this case, I put it on an old keg.
Very first cask ever!
And, finally tapped with a breather hooked up
This first one didn't turn out too well!!! I didn't get much conditioning in the cask itself, then let it vent too long, so it was a little flat. There is definitely a learning curve here!