making backport debs with dpkg-buildpackage

[Kai-Cheung Leung <kcleung@users.sourceforge.net>]

I have both GCC 4.0 and GCC 3.3.5 installed.  GCC 4.0 is intended for
future distributions and GCC 3.3.5 is intended for backport to sarge. 
When I invoke dpkg-buildpackage to build my debs, how can I specify which
compiler and which libstdc++ libraries dpkg-buildpackage to use?

Thanks,

Kai-Cheung Leung