How to install pg_trgm in Slackware 15.0

I have an application that makes use of the pg_trgm postgresql module. This module is not part of the postgresql package in Slackbuilds. I am rather ignorant about everything to do with postgresql, so I have no clue how this module can be installed under Slackware 15.0. Other distributions seem offer a package called postgresql_contrib that contains it, but I have not found anything like that in Slackbuilds.

Anybody in this forum know how to install pg_trgm in Slackware 15.0?