enable pl/pgsql in postgres from postgres-server-7.0.3-2 RPM

I installed Postgres from the 7.0.3-2 RPM on the Redhat site, and it
works well, and the plpgsql.so library exists, but how do I enable this
procedural language.

I know how to do it from source, but my customer demands I install from
RPM.

Thanks in advance.

Marc Wrubleski