Thanks for your reply Pete. I would have thought that since ERR has an email address, and it says to contact them about technical questions on that email address, that they would be able to help me with this. Definitely not the reply I expected.
Unfortunately I do not have a manual for the sound board. I have searched Lionel's manuals on line but can't find anything on this RS board. This is from an older RTR set and the sound board is controlled by the horn and bell buttons on the transformer. I am not sure how the serial output on the CC Lite board sends its signal, so I'm not sure if connection directly to this sound board is possible. I have read where the older whistle and sound boards need to have a separate circuit board to create the higher and lower voltage signal to control the horn and whistle. I have also read about them being connected directly to the board on the newer RS boards. Some show them soldered to a circuit on the bottom some on the top. Unfortunately, I haven't seen it done for my sound board. I was hoping some one had done this to one of these boards before. 
I have attached a picture of the board, if it will help.
