By cursor keys, do you mean the dpad?
Because the dpad pre-dates the N810. So, I would expect that the file where you manipulate cursor keys is a file that's common to both the N810 and the N800.
key <KPEN> { [ Return ] }; key <UP> { [ Up ] }; key <DOWN> { [ Down ] }; key <LEFT> { [ Left ] }; key <RGHT> { [ Right ] };