Well I haven't seen anyone do it on an Uno yet but I did read a page on doing it with another ATmega USB chip.
Somebody on these forums was playing around with some software to get the ATTiny (?) on the Uno (the controller that is the USB interface on the UNO) to act as a HID/Joystick/whatever device, soon after its release (like a week or so after).
At any rate - if that was solidified as an input option (ie, game controller) - this would probably be a good plugin to use for Cinema4D (not free, tho):
c4dplugin.com - Plugins for Cinema 4D - DirectControl plugin
