This might not be exactly what you are looking for, but I have an IR keyboard that has its own IR receiver built into a USB cable (http://tinyurl.com/ark8c5 on ebay). This works great for me on my N800.

I think the issue will be one of having drivers for the dongle. Since my keyboard has the receiver built into the cable it does not need any drivers, but your keyboard likely needs drivers to connect with the dongle.