https://tascam.com/us/product/us-122/download appears to have older PowerPC intel drivers from 2007 on their website.
You may want to give them a try or contact Tascam support if your 122 model is different than just a plain 122. Several Tascam 122 models exist, as you will find on this link:
https://tascam.com/us/support/download
Pick the one that is most like the one you have.
Note, if the deck simply has RCA ports, you might find it best to use RCA connectors to a USB iMic device from MacAlly.
These are easily integrated with software like Audacity and its LAME MP3 extension. If it is a Midi connector, you might find a USB-Midi adapter that you can use to connect the Mac to and manage it with your Midi capable software. There are quite a few on the market for that.