Dear Hernan,
Currently, just the 41 packages on the oacs-5-8 branch [1] and the packages in used on openacs.org (e.g. edit-this-page, workflow, bugtracker, photo-album) are adapted for PostgreSQL 9.3, for other packages this work is not done. Some packages of DotLRN might work out of the box, some will require work.
In case you want to install a fresh OpenACS 5.8.0 + Postgres 9.3 installation from scratch, check out the scripts [2] and replace in the configuration part of install-oacs.sh the "HEAD" branch with "oacs-5-8" to obtain the latest from the oacs-5.8.
In case you want to upgrade postgres of an existing installation to 9.3, see [3], but be aware, that not all packages might work; we are using on production system a modified version of dotlrn mostly with xo*-based packages with PostgreSQL 9.2, so we might be able to help you through the necessary modifications, when you tell us what exact problems you are experiencing.
all the best
-gustaf neumann
[1] https://openacs.org/repository/5-8/
[2] https://openacs.org/xowiki/naviserver-openacs
[3] https://openacs.org/xowiki/upgrade-oacs-5-8