That has worked perfectly.. Thx Stuart. Here is completed code...
public void SalesOrderForm_AfterDialogStart(JiwaFinancials.Jiwa.JiwaApplication.IJiwaDialog JiwaDialog)
{
if(JiwaDialog is JiwaFinancials.Jiwa.JiwaSalesUI.SalesOrder.PrintReportSelection)
{
JiwaFinancials.Jiwa.JiwaSalesUI.SalesOrder.PrintReportSelection printReportSelectionDialog = (JiwaFinancials.Jiwa.JiwaSalesUI.SalesOrder.PrintReportSelection)JiwaDialog;
printReportSelectionDialog.Manager.MakeReadOnly(printReportSelectionDialog.PrintToScreenCheckBox, false);
printReportSelectionDialog.Manager.MakeReadOnly(printReportSelectionDialog.OverrideNumberCopiesCheckBox, true);
printReportSelectionDialog.FormClosing += printReportSelectionDialog_FormClosing;
printReportSelectionDialog.PrintToScreenCheckBox.CheckedChanged += PrintToScreenCheckBox_CheckedChanged;
// printReportSelectionDialog.SingleReportRadioButton.Checked = true;
printReportSelectionDialog.ReportTypeRadioButton.Checked = true;
}