WP plugin mod - custom sort order for posts

I need an existing WordPress plugin called Business Directory Plugin to be modified very simply. [login to view URL] Currently it allows the user to create a form that the public can use to submit information for a directory web site. It uses that info to create a custom post type post with the status of “Pending Approval”. When published the plugin displays these directory listings ordered according to date of publication or the post title, id, author or modified, and ascending or descending, all according to settings in the plugin Directory Admin page. When installed go to Directory Admin on the left menu bar, then Manage Options, then Listings tab. Scroll down to Post/Category Settings. In my submission form I have a field named Date, for the date of the event. I need the plugin modded so it will allow sorting the custom post type posts by this event date field. The event date field from my form is displayed in the web page code in this way: Date: 03/21/1960 In the settings there is a dropdown where the user selects the sort parameter. Ideally, it would be nice to have an option for “other” which would then enable a new field in the settings page where the user can enter any form field name for a customized sort parameter for directory listings. If that is significantly more complicated to program, I would be happy to have the specific form field name added to the dropdown so that this will work for my specific form field name, which is all I need for this specific web site. This needs to be done as cheaply as possible, so don’t get too fancy, but let me know what you can do for various costs. To work on this you will want to install the plugin on a wordpress installation of your own. Looking forward to hearing from you.