If for any reason you are unable to access the Wacom tablet options in System Preferences, please follow the link below to download the latest drivers.
Mac Computers: http://cdn.wacom.com/u/productsupport/drivers/mac/professional/WacomTablet_6.3.11w3.dmg
Windows Computers: http://cdn.wacom.com/U/drivers/IBMPC/pro/WacomTablet_6.3.11w3.exe
Install them, and then restart the computer.
System Preferences should recognize the tablet and you should be able to continue with configuration.