Josh, it's all there already.

As root do:

/usr/sbin/apache

in an editor create this file:

<?php phpinfo(); ?>

save it as

phpinfo.php

and copy it to /www/var/

pop open a web browser and enter:

http://localhost/phpinfo.php

and there you have it: php and Apache working in perfect harmony.

I'll leave you to sort out MySQL yourself (it's already in Knoppix) , but there is an excellent manual and plenty of tutorials on line.