gEDA is installed using macports, but when installing i found a little problem when xgsch2pcb complained about a missing update-desktop-database
[important]fix: install desktop-file-utils first[/important]

complete install commands:

$ sudo port install desktop-file-utils
$ sudo port install geda-gaf
$ sudo port install pcb
$ sudo port install xgsch2pcb
$ sudo port install gerbv

useful addition: Mac OS X launchers for the commandline tools make it easy to start the apps and to double click documents, launches X11 and the responsible program:
http://www.msarnoff.org/geda-mac/