Don't think so - the PHP that runs on OSX is ported from unix - OS9 doesn't have a unix shell, it would have to be a specially written version. Unlikely, since nobody uses OS9 as a public web server; I'm not even sure there is server software for OS9 .. certainly not current if at all.
I'm guessing you want to run a dev server and the Mac is all you have? Perhaps you could install windows-emulator software and then run Windows Apache inside that ... dunno ... might work ...
"Why bother with accessibility? ... Because deep down you know that the web is attractive to people who aren't exactly like you." - Joe Clark