Modify free shipping notice extension to hide notice if certain items in cart

We are using the MagEvolve Free Shipping Remaing Cost extension found here: [login to view URL] The extension works as designed and the extension has a backend management page in System > Configuration. Observe the normal behavior with the extension working here: [login to view URL] We need the extension modified to accomplish the following: - We would like to add a multi-select field in the admin backend for the extension that says, "Suppress notice when cart contains items in these categories" and have all Product Categories listed to allow the user to select one or more categories. - The multi-select field would be added as the last setting in the extensions Display section in the backend. - We would like to suppress the notice on the front end when the shopping cart contains any item with a category matching any of the selected categories in the backend field. Budget is $75