Well, Greg's response came after I ordered the Dallee.
I decided not to gut my Mallet dinosaur style. Annoyingly, Radio Shack doesn't carry those 1 by 12 connectors, so I unsoldered the "DCC" connector from the little shorting PC board.
I was worried about the TE accessory receiver connecting directly to my 19.2v battery and I had a little 14.4v regulator I built for something else a while ago, so I ran battery power from the regulator in the tender to the outside pins of the dcc connector. I power the sound system, smoke, and lights from there. The light and smoke switches still work. I ran the output from the TE to the 3rd and 4th pins from the ends. I used dallee's magnetic chuff synchronizer with 2 magnets on the pilot truck.
The dallee board hisses, pumps breaks and pops the popoff valve. If I rotate the pilot wheels I hear it chuff. I can turn the bell on and off and blow the whistle with the te buttons. When the whistle is blowing, other sounds stop, but they continue when the bell is ringing.
My speaker distorts badly at really low volume, so I'm looking around for a better speaker.
Oh yea, with the top on, I can lift the steam dome and reach the volume control and code set button.