Change a printer driver of an already configured printer
This feature was removed in OS X 10.8. You have to use the CUPS interface by running cupsctl WebInterface=yes from Terminal and then pointing a Web browser to http://localhost:631. From there:


Open the Printers tab.
Select your printer and select Modify Printer from the second drop-down menu. (You’ll have to provide your OS credentials.)
Select your printer and click Continue twice.
Select a different driver or choose an appropriate PPD file.
Click Modify Printer.