The already installed Postgres edition was built using the same installation procedure as mentioned in the docs, but without the use of --with-perl flag. the point I ask the question is because I want to install PL/Perl as a separate extension as one does with PostGIS and not along with Postgres install. Is there a way out to solve that problem of building the PL/Perl language by somehow creating a custom Makefile as we have for contrib extensions or PostGIs etc... and then giving it the path of pg_config hence leading to an installation?