I feel frustrated because I did not log on to this thread over all this time. Casein printing is one of my favorites. This is just a short message, because I don't know whether any of you is still interested, but I will answer to any questions. I also once wrote an article on my technique in the postfactory photography journal.
A few of my casein prints can be seen at http://www.photographie.de/magazin/werth.cfm
One is a chrysotype printed over with casein.
I use the casein from Kremer, dissolving it with ammonia, dissolving 0.8 g casein in 10 cc household ammonia (european, about 9%).