This tutorial shows how to install and use suPHP with PHP4 and PHP5. suPHP is a tool for executing PHP scripts with the permissions of their owners instead of the Apache user. With the help of suPHP you can also have PHP4 and PHP5 installed at the same time which I will describe at the end of this article.
Read the full thing at http://www.howtoforge.com/apache2_suphp_php4_php5
As a note, apache-mod_suphp is available in Cooker, so to install you can do 'urpmi apache-mod_suphp'.