I tried this
@Html.EditorFor(model => model.Name, , new { data_bind = value:firstName });
and other possible overloades but none of them seem to work.

The rest of code:

<script type=text/javascript>

$(document).ready(function () {



    function AppViewModel() {

        this.firstName = ko.observable();

        this.lastName = ko.observable();

    }

    ko.applyBindings(new AppViewModel());

});