JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://raw.github.com/SteveSanderson/knockout/master/build/output/knockout-latest.debug.js"></script>
<script src="https://raw.github.com/SteveSanderson/knockout.mapping/master/build/output/knockout.mapping-latest.debug.js"></script>
<div data-bind='myWith: wrap'>
    Content: <span data-bind='text:innards'></span>
</div>

JavaScript

ko.bindingHandlers.myWith = {
    init: function(element, valueAccessor, allBindings, viewModel, context) {
        // change valueAccessor (an observable) to be extended
        return ko.bindingHandlers.with.init(element, valueAccessor, allBindings, viewModel, context);
    },

    update: function(element, valueAccessor, allBindings, viewModel, context) {
        return ko.bindingHandlers.with.update(element, valueAccessor, allBindings, viewModel, context); 
    }
};

// elsewhere
prototype_data = {
    wrap: {
        innards: "abc"
    }
};

bindings = ko.mapping.fromJS(prototype_data);
ko.applyBindings(bindings);