How to enable PL/pgsql for functions/triggers

I wanted to use PL/pgsql to write  functions for use with
triggers, and thought others might benefit from a concise description
of how to enable this without having to scour the postgresql
documentation.  This was with a default install of pgsql v6.5.2 on
RH6.0.

    CREATE FUNCTION plpgsql_call_handler () RETURNS OPAQUE AS
             '/usr/local/pgsql/lib/plpgsql.so' LANGUAGE 'C';

    CREATE TRUSTED PROCEDURAL LANGUAGE 'plpgsql'
             HANDLER plpgsql_call_handler
             LANCOMPILER 'PL/pgSQL';

Ref:  http://www.postgresql.org/docs/postgres/xplang.htm#XPLANG-TITLE

The trigger example at

    http://www.postgresql.org/docs/postgres/xplang19094.htm

does not work without this (there's also a missing single
quote after "AS").

Cheers,
Ed