I succeed to have open cascade work in a native cocoa application. It is a port focused on 3d opengl. (There is no OSX_DDriver equivalent to the WNT_DDriver). I big headache digging in OCC source code and some hacks in the occ opengl lib have made the deal.
Everything is working fine, visu 3d, visual transient or NIS view behave properly.
A big thanks to the peoples who have made OCC compilable on Mac OS X.
If there is some interest in it, I could release the port as LGPL or under OCC license (if allowed). I am not an expert in unix makefile so the code still sits in a xcode framework project. If anyone is interested in creating a patch for the 6.3 code base...