In order to activate mod_suphp support, /etc/httpd/conf.d/mod_suphp.conf
has to be edited.

The commented line "suPHP_AddHandler ###HANDLER###" has to be uncommented,
for mod_suphp to work.

After a restart of the httpd, php scripts should be executed with the
rights of the user owning them.

In case you do need mod_php support for a certain virtual host or directory,
you can selectively disable mod_suphp and fall back to mod_php:

<Directory "/var/www/html">
  suPHP_Engine off
  suPHP_RemoveHandler .php
  php_admin_flag engine on
  php_admin_flag register_globals on
</Directory>

This should do the trick nicely. The register_globals flag is purely optional
and should be avoided if possibly.

Should you require mod_userdir support, in order to enable ~user URLs, you should set 
check_vhost_docroot=false in the /etc/suphp.conf file, as currently suphp would fail
with an incorrect vhost.