I don't understand what is hard about this. I mean if you don't care about security, just make sure the mount has a umask of 770 (or whatever) and make an export, reload exports, and mount it from wherever you want.
What am I missing?
Also, if you want to call osx Unix, call it broken unix. Most people say its 'unix like' though. What I mean is that Apple changed basic unix commands around which osx not act right. And then it is possibly closer in comparison to windows than it is to Linux.