after the resistors, it goes to a simple amp/driver, than the 75ohm resistor to reduce the signal
simple amp/driver? is that built into the console or have to be added? and is the CV the LCD input?
Mixing Y (Luma), Red-Y, Blue-Y, and CB (Chroma Burst) is how the regular NEC console systems produce the Composite signal from the Hu6260 video encoder chip. The reason he has to ground all those pins mentioned is because those outputs are normally disabled (he figured out that grounding them re-enables them, etc.) for the portable. The new 3.5" screen needs a regular Composite signal, so it has to be produced in order to work with it. If he could connect the raw RGB to it, he would, but this is what has to be settled for, regardless, the new screen is far better and clearer even with the use of a Composite signal.
The NPN transistor that he's using is likely his favorite S8050 (as opposed to the #1 transistor in the world, the generic Radioshack 2n3904). Both work about the same, but steve says the S8050 is better in the long run and what not so I bought a pack of 100 myself for the mods that I'm gonna do (already finished my SNES YPbBr mod using it).
A picture of the S8050 is in this thread.
This image. But steve likely used the surface mount version, which is much smaller, but works exactly the same.