ControllerAction()
{
ViewBag.CheckBoxBlockMakeup = "<input type="checkbox""> // что угодно

}

cshtml
@section js
{
var checkboxes = @ViewBag.CheckboxBlockMakeup;

as.crud.init
...
...
...
Там где processRowAction
$("td["data-code='checkboxes']", row).append(checkboxes);
}