[boost] [serialization] Building for Borland problem

I downloaded the standalone Spirit 1.62 and put it in a directory of my machine. I set SPIRIT_ROOT to that directory in my environment. I then used bjam to build my Boost libraries for Borland and Bcb6. The serialization build reports errors from the spirit/core/config.hpp in my Boost 1.32 directory tree that my compiler is not supported. Of course I was expecting it to pick up Spirit files from my SPIRIT_ROOT directory tree. Why is this not working correctly ?