Very similar to normal DCC chips, only they have an additional 2 wires for the speaker.
Red & Black wires are for the track pick-ups, from the wheels, Orange & Grey are power feeds to the motor, White is connected to the headlights via a resistor, Yellow is connected to the Red rear lights with a resistor. Green & Purple wires are for the coach lighting and the Blue wire is the common Positive used with white, yellow, green & purple light feeds.
For the headlights I use 2mm Lighthouse LEDS - warm white and for the rear lights 2mm lighthouse LEDS - Red.
For the coach lights I use the warmwhite LED strips you can get from Maplins or Rapid.
I used two 4 ohm speakers, one for each coach, connected in series. I opened out the hole in the metal chasis of the units, to position the speakers in.
A lot to take in, I know, but give me a shout with a pvt message when your doing it and I can explain it bit by bit, if you like.
Dave