I successfully made it through that wikki for my gentoo box....
after you emerge everything, and add what you want to the default runlevel, you need to edit your httpd.conf file (or whatever it is in apache2)
Add the following lines if they don't exist:
LoadModule php5_module libexec/libphp5.so
AddType application/x-httpd-php .php
AddType application/x-httpd-php-source .phps
AddModule mod_php5.c
That should make PHP work with apache
you can always unmerge the php packages and then emerge them again if you think they're jacked up.