C840 Docking station audio

What is the trick to getting the audio to work on the C840 dock?  The dock itself has the line in, the headphone, and the mic jack on the side but none of them work.  I have checked the computer bios, and havent been able to find any setting to enable/disable the onboard audio.  I have noticed in the bios though the status of the computer is UNDOCKED even when it is docked.

Thanks

Rory