An alternate solution is to use 'styler' and 'formatter' functions to change column style and its displaying data. Here is the extended method to allow you to add custom class to specified field.
$.extend($.fn.datagrid.methods, {
addCellClass: function(jq, param){
return jq.each(function(){
var p = $(this).datagrid('getPanel');
p.find('td[field="'+param.field+'"] div.datagrid-cell').addClass(param.class);
});
}
});
Usage example:
$('#dg').datagrid('addCellClass',{
field: 'name',
class: 'myclass'
});