PHP (4.x) should work if the following lines exist in the httpd.conf (or in a file included by an include statement):
Assuming that libexec is the directory of the php module ...
LoadModule php4_module libexec/libphp4.so
AddModule mod_php4.c
<IfModule mod_dir.c>
DirectoryIndex index.html index.php index.htm
</IfModule>
<IfModule mod_php4.c>
AddType application/x-httpd-php .php4 .php3 .phtml .php
AddType application/x-httpd-php-source .phps
</IfModule>
Do you get an error about php when trying to start apache ?
Thomas