kickstart centOS 5.1 ---customization question

I am doing a centos 5.1 kickstart install for a school project and was wondering if there is a way to install a custom desktop background image.(upon 1st time logging into system)
(instead of showing the default centos desktop background, it would show a custom image)

Would i have to create a post-install-script that'll change the background?

Or is there an option in ks.cfg that I can edit to allow me to use a different background image?

You may look at the below link;

Kickstart Tools Introduction

Regards,
Anindra