Using Perl Code from PHP shows you how.

But given the simplicity of this script why would you not just do it in php and save firing up a perl interpreter to do such a trivial task?

Personally I think the most efficient way to handle this would be to have your script as a small mod_perl CGI so all you need to do in your pages is put a link to it. The old trick used to be to stick the link in an img tag and have the CGI return a 1 pixel transparent gif.

A log parser that runs across your access log will count pages quite happily for you and requires no changes to your pages.