I have tried to achieve same by below code, but after that ?Deselect? listener is not firing.
<ext:CheckboxSelectionModel ID="CheckBoxSM" runat="server" >
<Listeners>
          <BeforeSelect Handler="return BeforeApplicationRowSelect(item,record,index);" />
  <Deselect Handler="if (!#{GridPanelToolAdmins}.hasSelection()) {#{btnRemoveToolAdmins}.disable();}"/>
</Listeners>
---------------------------
        var BeforeApplicationRowSelect = function(item,record,index) { 
            var logOnUserId = document.getElementById('<%= hdnLogOnUserId.ClientID  %>').value;
            var logOnUserId1 = record.data['EmployeeId'];
            if (logOnUserId == logOnUserId1) {
                return false;
            }
            else {
                return true;
            }
        }

Please help in achieving same!