Here's what I use to set my keyboard.
Code:
# /etc/X11/xorg.conf.d/90-keyboard.conf ################################
Section "InputClass"
Identifier "keyboard-gb"
MatchIsKeyboard "on"
MatchDevicePath "/dev/input/event*"
Driver "evdev"
Option "XkbLayout" "gb"
#Option "XkbVariant" ""
Option "XkbOptions" "terminate:ctrl_alt_bksp"
EndSection
########################################################################
Try using that rather than the 'kbd' driver you're using in the file above (obviously changing 'gb' to dvorak).