Pgpool install - libpq is not installed or libpq is old

Based on the documentation here, I want to create a pgpool II with PostgreSQL databases. When I try to install, I encounter this error:

  configure: error: libpq is not installed or libpq is old

Searching the pgpool website, they mention to run ./configure with this command:

  --with-pgsql 

OR

   --with-pgsql-includedir

OR

   --with-pgsql-libdir 

But still I'm facing the same problem. Can anyone guide me what can I do from here?

I am running PostgreSQL 9.2 intalled from a yum package on CentOS 5.