Turns out CakePHP has a TimeHelper i18nFormat
function:
$time = time();
$timestring = $this->Time->format('Y-m-d H:i:s', $time);
$this->Time->i18nFormat($timestring, "%A %e %B %Y");
Create a file "LC_TIME" (no extension) and put it in your /Locale/ara/
folder (or replace 'ara' with whatever 3-char language code you want)
Copy the contents of CakePHP's time_test LC_TIME file and put it into yours (then save of course).
Then change it's contents to whatever language you want (I believe that example is in Spanish).
That's it!
Notes:
More details about the LC_TIME file here: http://pic.dhe.ibm.com/infocenter/aix/v6r1/index.jsp?topic=%2Fcom.ibm.aix.files%2Fdoc%2Faixfiles%2FLC_TIME.htm