To be able to use PHP software with AOLserver (and OpenACS), you have to install PHP with AOLserver support. Get the latest version from www.php.net. For convenience we get version 4.3.4 from a mirror

[root root]# cd /usr/local/src
[root src]# wget http://de3.php.net/distributions/php-4.3.4.tar.gz
[root src]# tar xfz php-4.3.4.tar.gz
[root src]# cd php-4.3.4
[root php-4.3.4]# cd php-4.3.4
[root php-4.3.4]#  ./configure --with-aolserver=/usr/local/aolserver/ --with-pgsql=/usr/local/pg74 --without-mysql
[root php-4.3.4]# make install
      

Once installed you can enable this by configuring your config file. Make sure your config file supports php (it should have a php section with it). Furthermore add index.php as the last element to your directoryfile directive.