Multiple instances of PHP 4 and 5

Hi,

I have a Linux Fedora server running PHP 4.3 and now have to deploy an application which needs 5.1. Whats the best way to go about this ?

I found quite a few threads (http://phpbuilder.com/board/showthread.php?t=10299413&highlight=PHP+linux) regarding this issue but not very helpfull or so old that it might have become obsolete.

Ideally, I would prefer to retain the PHP 4.3 version intact, install PHP 5 into a separate dir and load it in apache. how do I go about this ? I have both the tar.gz as well the rpm from http://rpm.pbone.net/index.php3/stat/4/idpl/1814120/com/php5-5.0.4-1.5.5.i386.rpm.html

And after configuring apache to load both PHP 4 and 5, how do I make my app to use PHP 5 ?

thanks,