We can change javascript key value to modify following script to trigger on any key (e.g. if change (code == 9) you can add new row with Tab key)
$(document).ready(function () {
$("#MyGrid").on("keyup", "tr", function (e) {
var code = (e.keyCode ? e.keyCode : e.which);
var td = $(e.target).closest('td');
if (code == 13) {
var tdIndex = td.index();
if (tdIndex == 3) {
var grid = $("#MyGrid").data("kendoGrid");
grid.addRow();
}
}
});
});