Comment 10 for bug 1030556

Fresh install of 12.10, all keys appear to work except Fn+F5/F6 (screen brighness). They're apparently dead in the keyboard driver,
as 'showkeys -s' doesn't respond at all when they're pressed, so there's nothing to map.

Fn+F3/F4 show up in the kernel keymaps, but not in X,
xmodmap <<EOF
keycode 229 = XF86KbdBrightnessDown
keycode 230 = XF86KbdBrightnessUp
EOF
works.