My reading of the annotated pictures in Modern Loco. Illus. is that the headlight is central with the tail lights to left and right lower corners. White marker lights for re-furbished engines are the dominos in the headcode box... or have I got this wrong?
To achieve this requirement requires the tail lights to be independent of direction of motion and dependent on presence of trailing load, not forgetting two engines running together (light or otherwise). Just adds to the fun of wiring and function programming... my skills in those aspects of DCC fitting are not that good so do not expect a decent / proficient solution too soon.
You are correct - the markers are in the former headcode panel, the tail lights are to the edges, with the headlight in the centre.
Be careful when calculating the resistors for the headlight (or any of the lights for that matter), they're not as bright as you might think they are! Don't ask me what I used for mine, as I can't remember and I'm not taking it apart to check
I'd recommend using a potentiometer to set the brightness on the bench and measure it using a meter, substituting the nearest available resistor value.
In terms of wiring, that's quite straightforward - what chip are you planning to use? The Zimo one that I used (MX 695 IIRC) has a nifty programming function where you can allocate all of the light functions in a sequence. It took me a couple of attempts to get it just how I wanted, but it seemed easier than faffing with a load of different CVs.
