Well it was pretty easy...
What I did for the FT-A was I purchased a Railsounds4.0 ERR F unit sound board from a fellow forumite foamer, and the first thing I tried was to swap the Railsounds board from the mother board. The R2LC, the Railsounds power board and the Railsounds board all plug into the mother board, and can be gently slid off and back on the long connector leads.
Unfortunately, they must have been different generations, so what I had to do next was swap the PIC and ROM chips between the boards.
The PIC and ROM are the large, black, flat J-leaded component (called QFPs or Quad Flat Packs) that press fit into Plastic Leaded Chip Carriers (PLCCs) and you must use a special tool called a IC (integrated circuit) puller (available from Radio Shack), as not to damage the fragile ceramic base material, the wire bonded leads or the plastic resin encapsulant. They must be kept in pairs...
Once I did this, and put the RS board back in, I reprogrammed the TMCC system to 36 (NYC F3, with cab light) and everything works great. The cab light comes on / off with 9 and 8, respectively, and AUX2 is the headlight.
Next on my list is to replace the generic diesel Railsounds from an Atlas Master NYC GP35 with a Lionel Railsounds4.0 sound package from an SD40.
Yes, I know that the RS4 are road name / number specific, and I know that it's an EMD 645, but I like the sound and I don't use crew talk anyway.
So when that comes Thursday, I'll do a before and after on that, as well.
Good luck!
- Mario