To configure XCache, edit ${PREFIX}/conf/php5.sample/xcache.ini.
To enable the module, create a symbolic link to that file from
${PREFIX}/conf/php5/xcache.ini:

ln -fs ${PREFIX}/conf/php5.sample/xcache.ini \
        ${PREFIX}/conf/php5/xcache.ini

If you already have Apache running on your machine,
you should not use "apachectl restart" - instead,
you should fully stop and then restart the server.