Objective-C++ Instance Variables

hi:

[sorry for the cross post - saw this group too late]

I'm trying to bridge between my Cocoa App and my C++ framework via
Objective-C++. Apparently I can't have C++ objects as instance
variables in my ObjC class because they contain virtual methods. Also,
I don't appear to be able to include my C++ header files in by ObjC
header file; they work fine if I include them in my implementation
file (.mm).

How should I create my C++ objects and use them within my ObjC class
(over it's lifetime)?  Perhaps I should be doing this a different way?
What I have is a C++ framework compiled into a dylib. I include the
headers in my .mm and link in the dylib.