Here's something you can try to see if you can get the pane working again.
1. Make sure the Wacom drivers are completely removed via the Wacom Tablet Utility app.
2. Download and install the legacy drivers (Driver 6.2.0-w4 for Mac OS X) at Wacom's Site
3. Change the System Preferences to open up in 32-bit mode (see below)
After you do this you should be able to open up the panel! Make the changes you need and then export the preferences from the Wacom Tablet Utility for future use (you know, when it stops working in the next Mac update). My biggest settings change is making sure the tablet forces proportions. Also make sure to uncheck 32-bit mode when you're done. This will, however, stop the pane from working though the settings should be saved.
Hope this works for you!