james young

Install MySQL on Mac OS X if you haven’t already
Install XCode if you haven’t already
Do either this:

Open NetInfo Manager
Modify /groups/wheel/users, add a new value for your login id, this will come into play later

or this:

$ niutil -appendprop / /groups/wheel users yourloginid

Get PHP Complete Source Code from php.net – http://php.net/get/php-5.2.2.tar.gz/from/a/mirror (more current versions are out now)
Open [...]

10.4.9

Edit the httpd.conf file
Uncomment the lines that contain php
Restart apache
Confirm it works via phpinfo.php
fix PEAR – see Enable PEAR on Mac OS X 10.4.x

command summary of the above (assuming you know what to do in vim)

$ sudo vim /etc/httpd/httpd.conf
$ sudo apachectl restart
$ vim /Library/WebServer/Documents/phpinfo.php

phpinfo.php contents

<?php phpinfo(); ?>