The adapter device that the SigmaStudio for SHARC Users Guide refers to as ADZS-USBI2EBZ is actually supposed to be ADZS-USBI2EZB (note the last two letters are switched). If you Google the former one, nothing will come up. Searching for the latter actually will take you to sites where you can buy these things. I'm not sure where exactly the error was made or which one of the two is correct, just wanted to point it out.
The correct part name is ADZS-USBI2EZB. Thanks for pointing this out.