After getting the CGI mechanism working with OliWeb, it wasn't that much of a stretch to add PHP support. I've just posted updates to GitHub for the as-yet-barely-tested capability.
I already know that the CGI QUERY_STRING is not compliant (I'm sending the full request plus arguments in the env variable instead of just the stuff to the right of the '?' which is what the standard calls for). I'm not sure whether this is going to cause problems for PHP but it will be easy enough to test out (fixing the QUERY_STRING CGI compliance has been on my to-do list for a long time anyways...).
https://github.com/m2ware/OliWeb
[UPDATE] There was really no excuse other than laziness for not fixing the QUERY_STRING to be CGI-compliant and I wanted to make sure that PHP wouldn't have any trouble with it, so I went in and fixed that. I added a PHP script and an HTML submit form to test proper passing / parsing of arguments through the CGI interface into PHP, which appears to work just fine!
