Joe,
I'm afraid that I can't directly answer your question, but one question about your issues looms large: Why are you installing your own GCC?
One possible answer is that you simply want a newer compiler. If that is indeed your situation, you should try "toolset=clang", which is Apple's newest and best compiler. (The darwin toolset, based on GCC 4.2 is currently maintained by Apple only for backwards compatibility.) Clang is, in my experience, an outstanding compiler and it has some of the most up-to-date support for C++11 available anywhere.
If your reason for using GCC 4.5 is something else, then I'm afraid you'll need help from some of the Boost.Build gurus themselves.
-Ian
_______________________________________________
Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost-build