changing default compile options

[David Fuess]

I am building a Fedora Core 4 server that uses apache 2, php 5, mysql 4, 
gd, and trueFont. The problem is that the default package installs do not 
contain all of the required oprional features (like mbstring, libpng, gd 
etc. for PHP). The single biggest problem at the moment is PHP because 
without mbstring I even have problems with phpMyAdmin. What is the best way 
to go about "upgrading" the installed packages to include the correct 
optional features?