You might start here to do it the way they really did:
http://www.subsim.com/radioroom/showthread.php?t=106923
Also there is some evidence that even the early fleet boats didn't have a TBT until 1943, or even 1944:
http://www.subsim.com/radioroom/show...ng+transmitter
(note that 'Torpex752' is the same Frank Kulik who wrote the Valor At Sea article, and also one of the very first SubSim members)