Great that you're able to do it. I've tried everything without success. Thinking of buying a printer that has 11x14 in it's menu choices. I think the problem is with Qimage not Canon. The printer is a dumb piece of equipment that will print whatever you feed it.
The "problem" as you defined it is that the driver doesn't support 11x14 paper. How can that be the fault of Qimage? It would be well advised to learn how to use your printer and driver as those will be a prerequisite to any software you decide to use: all software uses the same driver and the software has to obey the capabilities of that driver/printer. 11x14 media not supported in the driver: it will not be supported in
any software that uses that driver. Once you are familiar with drivers and how they work, there are some tricks you can do to "fool" the driver into printing on 11x14 paper: for example, select 11x17 in the driver (the closest the driver will allow) and then select borderless. Then in Qimage, enter a 3 inch bottom margin: this defines an 11x14 area at the top of the page. Then print by feeding the printer 11x14 paper even though 11x17 size is selected.
Regards,
Mike