Add motion effect to background image in joomla

I have a joomla 1.5 template ready and I would like to add the background motion effect like in this template [login to view URL] I have the images ready in png transparent files and I would like to have the same motion effect in my background. I believe the template uses mootools but I am not sure which functions in particular. I assume that the rest functionality in my template will continue to function as before after the motion background. I think it is a fast project for someone who has done this before. Please give me samples of relevant work (motion background) I will give more details in PM to those who are serious bidders.