Open

<input id="multicolumncombobox" />
<script>
$("#multicolumncombobox").kendoMultiColumnComboBox({
  dataSource: [
    { id: 1, name: "Apples" },
    { id: 2, name: "Oranges" }
  ],
  columns: [
    { field: "name" },
    { field: "id" }
  ],
  dataTextField: "name",
  dataValueField: "id",
  index: 1
});

var multicolumncombobox = $("#multicolumncombobox").data("kendoMultiColumnComboBox");
multicolumncombobox.open();
</script>