To install PHP for the runtime version of PAW, download the file PawRuntime_PHP_Setup.zip (link below) and unzip it to /sdcard of your Android device.
After starting PAW Runtime a PHP menu entry should be available.
After selecting the entry the page shown below should appear...
If you wold like to get rid of unnecessary files and the menu entry, you can delete the file /sdcard/paw-runtime/webconf/apps/php_setup.conf and everything inside the /sdcard/paw-runtime/html/php_setup directory except the conf directory.
If you have problems to download above files from the original source, try to use the alternative RapidShare links below: