This is a dedicated video capture device. Do the specs of indicate that it can record audio outside of a DV stream? Is it a Core Audio compatible device? I take it it is not recognized as an audio device in the Sound preference?
I'll leave it to someone who has one of these to go into the particulars of any workarounds, but I think the only way is going to be to capture the sound as a movie with no picture, and then extract the sound from the movie file with some software.