All process could be easely found in the web. For example read this http://jason.pureconcepts.net/2012/10/install-apache-php-mysql-mac-os-x/ or this http://coolestguyplanettech.com/downtown/install-and-configure-apache-mysql-php-and-phpmyadmin-osx-108-mountain-lion
What else you may need todo:
1. edit User and Group in /private/etc/apache2/httpd.conf or you could get some strange permission errors. find in you httpd.conf and change to this:
User username
Group #-1
2. Edit you /private/etc/php.ini ... I just copied my old one :)
