The Sherwood RX-4105 uses the standard Sherwood setup code Audio/0491 and (as you've discovered) the urc-9910 is one of the few models that DOESN'T include that setup code.

It's quite easy to add via JP1 cable if you had one, and it's not TOO hard to create a .wav file using JP1 (free) software without the cable, and to install the that setup code into the 9910 from you PC's speaker. But waiting till Monday and having customer support play the .wav for you over the phone would be easier.