http://bugs.winehq.org/show_bug.cgi?id=35224
--- Comment #24 from Luke A. Guest laguest@archeia.com --- In the Rocksmith.ini change:
ExclusiveMode=0 Win32UltraLowLatencyMode=0
The second line forces the game not to use defaults, so you can set it to shared mode, as exclusive mode will not work with a callback.
It initialised the device at this point, but still thinks the cable is disconnected when you go to the tuner.