Hi I just compiled the lastest version of php (version 4.3.1) on my empeg.
The binaries can be downloaded from http://empeg.homelinux.com/php.tar.gz.
Just unpack it and set the library path:
export LD_LIBRARY_PATH=/opt/phptest (adapt directory)

Run the testscript by calling:
./php test.php

Maybe some library are missing. If so please send a reply to this message.
I compiled it with the default settings plus mysql support.
It should work in the normal empeg environment.

I'm running a complete debian chroot installation on my empeg since last october. The webserver you download the above files from are running on my backup empeg. (Apache + PHP 4.1.x) [There is no stable debian package for PHP 4.3 at the moment]