The wikipedia article is good, then try this pdf:
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.148.6425&rep=rep1&type=pdf
I was also able to find a picture of the prototype system that one of the author's fellow grad students built.
The cycle is similar to the Electrolux cycle that is used for propane-powered RV refrigerators. In fact, the Electrolux corp bought the patent rights from Einstein and shelved the technology without ever developing it.