No, it won't affect your Dingux install (in case you're worried, you can plug of the sd card, update native firmware and plug it again after).
V1.22, this things can be found in a quick search in google.
And you can find instructions also using google: http://boards.dingoonity.org/dingoo-help/how-do-i-update-firmware/
It's the same process regardless of the firmware version.
It's not easy to give "more" details if you don't tell what step you don't understand. Try to do it and if you get stuck, ask for that particular step.