You will need a computer running a unix-like system with the following software installed:
tdom
tcl
gmake and the compile and build environment.
BSD users: in most places in these instructions, gmake will work better than make. (more information on FreeBSD installation)
and optionally these programs, which are included in most distributions:
emacs
cvs (and initialize it)
ImageMagick
DocBook and supporting software (and install emacs keybindings for DocBook SGML)
daemontools (install from source)
a Mail Transport Agent, such as exim or sendmail (or install qmail from source)
To install a machine to the specifications of the Reference Platform, do the walkthrough of the Red Hat 8.0 Install for OpenACS.