I've never answered this question before. To be completely honest, I've never tested it on PHP 5.2 and COPS was my first PHP project so I won't be able to help you a lot here
I'm happy it works as expected :P
I never checked but I assumed the API also existed with PHP.
I know there was a fork of COPS on Github which can access the public part of Dropbox (that way it's easier to install on shared PHP hosting). I'll maybe merge it as a first step.