OS Commerce contribution help

I have an OS Commerce site and need someone to install a contribution that is available in the Forums section. It requires knowledge of PHP and SQL, which I have none. Should be easily installed but my site was modded so its not working and I can't figure this one out. Here is the link [login to view URL],3607 When a customer selects a country, I need the pulldown menus to filter the states in that country. As it is now, customers have to scroll through a long tiresome list.