Hi Richard,
Great it helped.... If you don't see a property for that option in the System..Printing then OKI doesn't expose it through their .NET Print Driver.
FYI - CR Designer uses the DEVMODE structure to access the printer, .NET uses the .NET Framework equivolent in System.Drawing.Printing.PrinterSettings
So if the FW doesn't expose the property you won't be able to change it.
Possible work around, see if there is an option in the printer driver by adding a new printer and changing the default to Utility mode. May work for you.
Try using the POC Method to do the printing, it uses an ActiveX dll that may be better capable of not switching to NLQ mode.
Don