on the Gopro Hero2, which we have, there is a audio In on the side of the camera, you can get a cheap adapter, that you can plug inline with the speaker line and records all you hear through your headset to the camera. its then a simple matter of syncing up the audio with the forward looking camera with some editing software. the headset is pluged into the aft looking camera.
like this one
you can drill a hole in the side of the housing, or buy a skeleton housing with cutouts for access to ports already made