use gcc4.x and libstdc++5 together

[hg-thien]

I have to use gcc4.x and libstdc++5 together -  but gcc4.x uses 
libstdc++6 per default

This requirement comes from the fact that:

  - we are using a 3rd party binary only shared library which was linked 
to libstdc++5 (produced by gcc-3.3 I suppose)
  - we cannot use gcc3.3 because it lacks some advanced features from gcc4

Although our application compiles and links fine I have some concerns 
that mixing libstdc++5 and libstdc++6 might be a bad idea. And indeed, 
the ldd command shows that both versions of libstdc++ are used.

I have tried to get rid of libstdc++6 by using the command line switch 
-fabi-version=1, but ldd shows that libstdc++6 is still  in use afterwards.
 
Is there a way to force gcc4.x to use libstdc5++.x instead and to ignore 
libstdc++6.x?