In another discussion Tascam responded to a customer with this:
Dear Customer,
Unfortunately that unit has been discontinued for a few years now and we are no longer developing drivers for it but you can boot Mac OSX Lion in 32 bit mode which should make the US-122 work on the system as long as you have the latest drovers installed. To boot the Mac in 32 bit mode hold down the 3 and the 2 buttons while starting up.
Thank you for your interest in Teac/Tascam products. If you need further assistance feel free to call us at 323-727-7617 or e-mail us at Custser@teac.com
Which along with the last driver being loaded in 2010 I'm going to say if you do get it working good luck. I suppose the 32 bit mode might get the driver to respond - but I don't think I would trust it. Time to move on IMO.
For the record that is referring to the US-122 which is an older model than the 122-L. In any case, this is the company line that I received a few days ago after I had figured it out on my own:
I recently did some tests with that unit on Mac OSX Lion and it seems to work properly. Uninstall any drivers you have installed and install the 2.00 driver. Make sure the latest firmware version is installed, which is version 1.12.
You can download the latest drivers/firmware for that product at:
http://tascam.com/product/us-122l/downloads/
Granted, I've only tried to use it in Logic Express and no other program, but I can definitely tell you that I can record with my condenser mics,and hear playback through my monitor headphones, which is all I needed it for anyway since my keyboard is USB.