I got mine to show up as an alsa device w/11.10 on a Dell inspiron 1525 (pretty much stock) with the following protocol:
Follow the Mediabunto repository instructions:
https://help.ubuntu.com/community/Medibuntu
Specifically, use this command:
sudo wget --output-document=/etc/apt/sources.list.d/medibuntu.list http://www.medibuntu.org/sources.list.d/$(lsb_release -cs).list && sudo apt-get --quiet update && sudo apt-get --yes --quiet --allow-unauthenticated install medibuntu-keyring && sudo apt-get --quiet update
once that's completed execute the following commands:
sudo apt-get update
sudo apt-get upgrade (say yes, this will update your system, may take a bit)
sudo apt-get install alsa-firmware-loaders alsa-firmware
At this point, plug in the US-122 and it should be detected by the system and the drivers loaded.
You know it worked right when you execute:
cat /proc/asound/modules
and there is a line in there referring to snd_usb_usx2y
however ymmv, i can address this in Jack (and record to Rosegarden fine) but when using alsamixer and selecting the Tascam device, it claims there are no settings available.