Here you can find full UKNC ROM disassembly made by Alex_K:
http://www.emuverse.ru/wiki/%D0%A3%D...%A6_ROM_disasm
Here's part 2 with keyboard driver where you could find keyboard layout tables:
http://www.emuverse.ru/wiki/%D0%A3%D...6_ROM_disasm_2
So (in theory) you could try to alter the layout tables, then re-calculate ROM checksums at (176770..176776), probably that's a suitable solution.
But that's a significant amout of work to prepare the proper ROM alterations, test the new ROM on the emulator, burn to ROM chip and test on the real hardware.