Rejetto is right. That won't be possible until PHP is implemented directly into HFS. This method is only for simple PHP commands or in-line scripts. Each command takes roughly 0.07 seconds, so loading up a page with tons of php commands will make a very slow page. What you can do with this is very limited, but it still opens up a few possibilities.
That being said, if you were to take the time to reprogram a PHP script to use just argument variables in place of URL Variables, posted variables, and cookies, then it could theoretically be possible, but not practical.