Actually there is no need to install PHP its already there you just need to enable it. search for " Restoring the Apache config file after 10.2.4 update" on www.macosxhints.com and read the reader comments. Many will say why not just read the tutorials that tell you how to edit the httpd.conf file to enable it. Beacuse I have done that and everytime you upgrade the system you have to do it again. The reader comments explain how to create an overide.conf so it will stay enabled even after you update your system. If you are a little command line nervous and didn't want to go the path above you can search on www.versiontracker.com for "CompletePHP" You will be taken to Aaron Faaby (sic) website where he has complied click installers with control panels to install and control PHP, MYSQL, Tomcat and even Apache.
Just throwing out some more options.
Good Luck Hope this helps