There is a program called Fink, which lets you download and install many Unix programs on OS X. Some packages are available as binaries, others will be installed in source form, including compilation and such.
You need a compiler and other goodies. Maybe you got the developer tools on a CD with the rest of OS X, if not, you need to download them from Apple. Since they get updated every once in a while, you might as well download them regardless. Go to connect.apple.com, free registration required.
Goto fink.sourceforge.net and download the thing.
Open your terminal, and try fink list. Then do fink install for some package. You probably need to start with xfree86, installation of which will keep your machine busy for a few hours.
Packages are classed as stable or unstable. In spite of the name, you might as well use the unstable packages, because that is where bugs get fixed quickest. Read the web page to find out how to let fink consider unstable packages.
Is there an ftp URL listed? Open that URL in your browser and see if fink tries to load an older version than the one available on the ftp site. If so, do fink selfupdate so that fink knows about the latest version, and try installing again. If the version on the ftp site is older than the one fink tries to load, choose the Retry from another mirror option.
You have to do "fink selfupdate-cvs". If you just do "fink selfupdate",
it only updates if there is a new complete *release* of the whole fink
distribution. "fink selfupdate-cvs" gives you the possibility to get the
continual updates of the various packages also in between point
releases.
Fink works by downloading .tar.gz files into /sw/src, then unpacking them. So you can actually put tar files in that directory yourself, then telling fink to update.
This file is part of Victor Eijkhout's OS X notes.