[TxMt] Web Preview w/ PHP includes and CSS / images?

I'm sure this has been asked a number of times, but I can't seem to locate any answers after searching extensively through the list archives and online.

I'm trying to get the web preview window to a) display relatively linked images and CSS files, and b) process all PHP includes referred to in the file.

I've got the first one working by using Thomas Aylott's ruby script, but I can't seem to get the PHP includes working at the same time.

Can anyone put me out of my misery and give me an idea of how to get this working? I've got TM_PROJECT_SITEROOT and TM_PROJECT_SITEURL set properly.

Thanks!

Neil