I have a similar problem with a Logitech Cordless Desktop Wave Pro
My understanding is that xev can only see scancodes below 256 and these keyboards do 2 byte codes which need to be re-mapped.
I have Fedora 16 and there are two files that might help.
You cam copy the /lib/udev/rules.d/95-keyboard.rules to /etc/udev/rules.d. Using these enhanced rules for keyboards, if udevd detects your specific keyboard it may load a vendor specific keymap and allow these extra keys to work. These vendor specific keymaps are in /lib/udev/keymaps/. In my case it loads the logitech-wave-pro-cordless
BTW I am still trying to get this to work.
I see a few Lenovo keymaps in there, but you'd have to map what the rules say against your specific keyboard.