You can easily install the intl international support extension to PHP 5.4 on Mac OS X 10.9 Mavericks Server. Here’s how:

Download and install MacPorts from http://macports.org.

The following steps are performed in the Terminal:

Force MacPorts to update:

sudo port -v selfupdate

Now, install intl:

sudo port install php54-intl

Next, you need to edit /etc/php.ini to add the extensions. Find the phrase Dynamic Extensions, and add:

extension=/opt/local/lib/php54/extensions/no-debug-non-zts-20100525/intl.so

And finally, restart Apache:

sudo apachectl restart

To confirm installation, create a new PHP document called phpinfo.php with the following contents:

<?php
 phpinfo();
?>

Point your browser to the URL of that file. If all went well, you’ll see this block: