You can connect onblur event and in callback function set particular textbox as readonly or editable.

$col["editoptions"] = array("onblur" => "update_field(this)");

<script>
function update_field(o)
{
if ($(o).val() == "YES" || $(o).val() == "UNCERTAIN")
$("#particular_column").attr("disabled","disabled");
else
$("#particular_column").attr("disabled",false);
}
</script>

For inline editing, you will also need to set like:

$("input[name='particular_column'].editable").attr("disabled",false);

You can inspect the field id.using firebug and use jquery functions to disable / enable desired field.

To know jquery selector:
http://easycaptures.com/fs/uploaded/1017/9892108434.png
http://easycaptures.com/fs/uploaded/1017/9617668813.png

It don't work. pls see my code as below

$col = array();
$col["title"] = "回來時間";
$col["name"] = "in_time";
$col["width"] = "50";
$col["editable"] = true; // this column is editable
$col["editoptions"] = array("size"=>20); // with default display of textbox with size 20
//$col["editrules"] = array("required"=>FALSE); // required:true(false), number:true(false), minValue:val, maxValue:val
$col["editrules"] = array("custom"=>true,"custom_func"=>"function(value, label){return my_validation(value, label);}");
$col["formatter"] = "datetime"; // format as date
$col["formatoptions"] = array("srcformat"=>'H:i:s',"newformat"=>'H:i:s',"opts" => array("timeOnly" => true));
$col["search"] = true;
$cols[] = $col;

$col = array();
$col["title"] = "即日返回公司";
$col["name"] = "back_to_office";
$col["width"] = "50";
$col["search"] = true;
$col["editable"] = true; // this column is not editable
$col["edittype"] = "select";
$col["editoptions"] = array("value"=>'Yes:Yes;No:No;Uncertain:Uncertain', "multiple" => true, "onblur" => "update_field(this)");
$col["align"] = "left"; // this column is not editable
$cols[] = $col;

<script>
function update_field(o)
{
if ($(o).val() == "No" || $(o).val() == "Uncertain")
//$("#in_time").attr("disabled","disabled");
$("input[name='in_time'].editable").attr("disabled",false);
else
$("#in_time").attr("disabled",false);
}
</script>