interactive backend output

Im trying to understand the internals of postgres a bit better. Right
now, im piping the stdout of the postgres binary to another
application. That app parses whats returned from qyeries and such. I
would like for the postgres binary to act as if it was started by the
postmaster and output to stdout the same data it would send to the
postmaster. Can anyone point me in the right direction on how i might
do this. I have the source and have been playing around with it a bit,
just for learning purposes, nothing special.

thanks!

Alex