Directory Press Modification

I need a modification of the categories script in Directory Press (via Word Press) to make accessing options easier. As of now there is one top level option and two sub options (State, City, Type) all listing go into the third level category. As of now when a user goes to click the drop down all categories and sub categories are showing making finding where your listing needs to be a little daunting. I need the code edited for the top level to show, then once chosen the second tiers to show and then finally the third tier. This is Wordpress with the Directory Press plugin.