I bought an Avermedia USB FM radio for my setup,
http://www.pocket-lint.co.uk/review.php?reviewId=502.
A friend and I found out that it got the ground signal, needed for Left and Right sound channels from the USB, and used the then free pin in the headphones as antenna. So, the headphone cable had another cable, quite long, which worked as anttena. Maybe this one does the same trick.
We didn't try it in a car, though. Software control with Fairy Radio wasn't as good as with the mythical D-link one.