Here is a sample XKeyboard Definition to include inside the Keyboard Section of your XF86Config File.
Xkbkeycodes "xfree86"
/* XkbSymbols "us(pc101)+de_nodead" */
/* This has changed between 3.1.2E and 3.1.2F */
/* it is now: */
XkbSymbols "us(pc102)+de(nodeadkeys)"
XkbTypes "default"
XkbCompat "default"
XkbGeometry "pc"
or you could use this one with the new Options:
XkbRules "xfree86" XkbModel "pc102" XkbLayout "de" XkbVariant "nodeadkeys"