aL,
You choose 'UVI Workstation' for the input on an instrument track. Just like you would choose any virtual instrument. Once UVIWorkstation is there, you click right in the middle of the label to open up the UVI interface. Then you can load up the B-5.
It works for me using MS3 on my Macbook Air from 2013 (just barely - CPU is maxed but no clicks/pops).