Gilbert,
you'll find the necessary files in the openacs.org-dev repository. These changes haven't been comitted to openacs-4 repository. Checkout a copy of the packages/forums/sql/postgresql/ directory in the openacs.org-dev repository and move the forums-sc-create.sql and forums-sc-drop.sql files to your openacs-4 copy of the forums package.
Then run the forums-sc-create.sql script in your database to enable openfts searching.
The ETP pages are searchable by virtue of the content repository (CR). However, link to the indexed content as returned by the content repository uses CR templates. If that is not what you want then read https://openacs.org/forums/message-view?message_id=68487.
/Bart
