This tutorial explains how to import products magento using script.Here products are importing from opencart to magento using the script.I have exported the following CSV files from the opencart backend.
This script import all the categories, attribute and the products to magento. Its also create the simple and configurable products and assign that to the new categories. Here I am also importing the related products as well.
In this tutorial explains how to add a featured product custom attribute field to the product section using the install script.Please also refer the tutorial which explains how to add custom options to the dropdown.
You can also add the attribute to product page using the magento backend Manage Attribute section.But if you add using the setup script it easy to move files from the development database to live without copy the database changes manually.