If you want to avoid editing the file on the Nokia then you can copy the input.ini file onto the RS-MMC card with xterm to /media/mmc. If you then connect the Nokia to a PC with the USB cable then you can edit the file on your PC (make a backup first) as the Nokia's memory card shows up as a hard drive. Finally copy back the input.ini to /home/user/.opera.

Having said that, editing the file on the Nokia isn't difficult either...