Whoa, I figured it out! Not sure if it was something I did but the most recent time I loaded the live cd, it put the stupid MyBook in the sdb1 slot and then I ran PhotoRec from the media directory instead of the home/knoppix directory. This time it showed me all the options in a way that made sense and I could even navigate to a specific subdirectory in MyBook to write the files. This was probably something really obvious to a Linux user...or even someone really familiar with command line stuff. In any case, PhotoRec is running!

So now I just cross my fingers and pray to the voodoo computer gods that it can find anything!