Ajax category Location select II

I have a directory which has locations and categories dependable ... Need a chain drop down .. meanning not to list all categories and subcategories in the drop down . Only first the main category then based on the selected main category it shows the subcategory etc.. Same for the locations. I have this on few forms that needs to be updated.. Currently it looks like: [login to view URL] THe modification should be easy to use/install you can work on a test site. Feel free to ask if you have any questions. Thanks,