@billm:
Does FreeBSD even support it? When there's an in tree driver, we can add it to our driver list - we aren't going to ship binary blobs or apply non-BSD licensed vendor patches to make this work. FWIW, usb ethernet adapters do work, if the cable modem presents itself as a supported usb ethernet adapter, then it should "just work". Give it a try, worst case is that is just won't work and you've cost yourself 15 minutes of play time on the livecd (alot less than this discussion has taken I'm guessing).
–Bill
It is autodetected as a USB network card in IPCop.
I'll give it a try when I get home.