Lots of ways to do it . Most use it like a big carboy. Put an orange carboy cap on and you're good to go.
I use the "slim" quarter kegs. They are 7.75 gallons, as tall as a pin-lock, and a little wider.
Brewers Hardware also sells a stainless cap to use.
Brewers have also cut out the top and made a pressure lid for it. Others have welded on a corny top.
I like to keep it simple. YMMV
P.S. you can use cornies too.