For recent kernels, get /pub/Linux/system/Keyboards/kbd-0.90.tar.gz from ftp://metalab.unc.edu/. Make sure you get the appropriate version; you have to use the right keyboard mapping package for your kernel version. For older kernels you have to edit the top-level kernel Makefile, in /usr/src/linux/. You may find more helpful information in
The Linux Keyboard and Console HOWTO, by Andries Brouwer, at ftp://metalab.unc.edu/pub/Linux/docs/HOWTO/.