Prerequisites. Install readline:
Download readline from http://ftp.gnu.org/pub/gnu/readline/readline-4.3.tar.gz into /usr/local/src
Extract readline in /usr/local/src, configure, compile, and install:
su - root cd /usr/local/src tar xvfz readline-4.3.tar.gz readline-4.3 ./configure make make install
Proceed with the Unix-like system instructions. OS X is incompatible with Oracle 8, and Oracle 9i on OSX is not yet verified for OpenACS. So continue with Install PostgreSQL. Additional special steps for OS X are documented inline with the standard Unix-like instructions.
Additional resources for installing on OS X.