Edit in JSFiddle

var flexGrid = new wijmo.grid.FlexGrid('#FlexGrid');
flexGrid.itemsSource = createData(10);
flexGrid.itemFormatter = function (panel, r, c, cell) {
  if (panel.cellType == wijmo.grid.CellType.Cell) {
    if (c == 4) {
      var checkbox = cell.firstChild;
      // Countryが'US'の場合、チェックボックス非活性
      if (panel.getCellData(r, 1) == 'US') {
        checkbox.disabled = true;
      }
    }
  }
};
flexGrid.beginningEdit.addHandler(function (s, e) {
  // Countryが'US'の場合、編集をキャンセル
  if (e.col == 4 && s.getCellData(e.row, 1) == 'US') {
    e.cancel = true;
  }
});

function createData(count) {
  var countries = 'US,Germany,UK,Japan,Italy,Greece'.split(','),
      data = [];

  for (var i = 0; i < count; i++) {
    data.push({
      id: i + 1,
      country: countries[i % countries.length],
      date: new Date(2014, i % 12, i % 28),
      amount: Math.random() * 10000,
      active: i % 4 == 0
    });
  }

  return data;
}
<div id="FlexGrid"></div>