Dell Printer C1765nfw issue with custom paper size setting

I want to set one of the custom page size settings to A9 (5.5 X 8.5 inches). The instructions state that the settings must be registered as "custom". Once the new size is registered it can be selected in the paper size on the layout tab. However, further investigation states that in order to register the new size setting, it needs to be accomplished using the printer driver. I did not find any instructions that provide more specific information. I also tried to download a driver for C1765nfw but Dell support displays a message stating that no driver exists.