Apache and PHP are pre-installed on Mac OS X client, but disabled by default. The following should work for Tiger (10.4.x) and Panther (10.3.x) client (if there is no previous version of DokuWiki installed):
$ sudo cp /private/etc/apache2/httpd.conf /private/etc/apache2/httpd.conf.bak $ sudo pico /private/etc/apache2/httpd.conf
$ cd ~/Desktop && tar -zxvf dokuwiki-yyyy-mm-dd.tgz $ mv dokuwiki-yyyy-mm-dd ~/Sites/dokuwiki $ cd ~/Sites/dokuwiki $ sudo chown -R www data conf
You should now be able to run the installer at http://localhost/~your_username/dokuwiki/install.php
For Tiger (10.4.x) and Panther (10.3.x) server:
$ cd ~/Desktop && tar -zxvf dokuwiki-yyyy-mm-dd.tgz $ mv dokuwiki-yyyy-mm-dd ~/Sites/dokuwiki $ cd ~/Sites/dokuwiki $ sudo chown -R www data conf
You should now be able to run the installer at http://localhost/dokuwiki/install.php
The third-party Apache2 package runs as 'nobody', not 'www' – change your chown command accordingly
When editing any config files manually, make sure they are saved with UNIX lineendings (LF) not Mac lineending (CR)
There is a somewhat outdated HOWTO for DokuWiki on Tiger available
What about MacPorts? Can anyone offer guidance there? (the MacPorts documentation is sparse on everything, so some help here would be nice)