Kevin,
I've been busy catching-up from my York trip, and just stumbled across this thread.
For the record, those are RailSounds 2.5 boards, and they're fully TMCC-compatible. I spelled-out what you need to do in an e-mail a few weeks back, but if you didn't get it, here are the instructions again:
1) Make sure the power polarity is the same between the RailSounds and your ERR boards. On the RS board you got from me, red goes to the center rail and black to the outside rails.
2) Take the serial line from the RS board (in the four-pin power connector, it's the loose wire coming from the opposite end from the center rail lead) and connect it to the serial line output from your ERR Commander. I just looked up what that would be, and I've labeled it here: