I didn't find any further documentation per say, but I have spent a great deal of time in the ZEND development platform, looking at code, and forming a mental map of how everything fits together.

I was going to try to port code from OSC, but I found an easier approach to be just inspect the modules available for download, and look at their structure, and get a feel for the tables in ZC and their relationships. I did have some success with the mod for gift registry, wish list but I did a lot of custom php code and changed it's functionality quite a bit :-S

good luck with your search...