Disable the checkbox column in DhtmlxGrid

Suite and Optimus Suite 5
#1

i am creating a checkbox column in grid.Once the grid is loaded i want to make the Checkbox column disabled how do i achieve it

#2 
mygrid.load("grid.xml", function() {
  mygrid.forEachRow(function(rId){
    mygrid.cells(rId,{colIndex}).cell.down('input').disabled = true;
   });
});