Since custom bindings modify the ko
object, they only need to be loaded once, and their modules do not need to return anything. If you have a main/entry/app section as the first step in your app, simply requiring your custom bindings and extenders is all you need to do.
define(['jquery', 'knockout'], function($, ko)){
// Custom Bindings
ko.bindingHandlers.returnKey = { ... }
//NO return needed
});
Then, in your startup section, just
require('lib/custom-ko-bindings');