Hi Jay
I use tinned cat food for berley (groundbait) more when sea fishing, just suspend a tin in an onion bag with holes punched through it, into the water, let all the juices leak out and set up a trail. For the method i think you'd use chunkier types, well chopped and mixed with crumb or the like. Not sure about PVA bags as it's fairly wet stuff, unless your a quick cast.
Martin