SCART to component video, then composite video signal conversion without ICs

My goal is to see if I can convert the RGB signals of a scart connector used in this project **broken link removed** to composite video without using any ICs.

I have found the next information:
a. videosignals pp5
b. an57fa pp7

in the videosignals pp5 the possible conversion way is shown. And in the an57fa pp7 a component video converter is shown (as a first step).
Note that in the computer schematic Hsync/Csync and Vsync signals are available too.

Now I wonder, can I do the component video conversion by not using ICs at all but just simple transistor circuits, based on the application note?
But don't tell me to replace the opamps with discrete transistors, I mean something simple. Great performance isn't an issue to my case, simplicity is more important even if the colors are not very accurate.

Color video circuits can be done with discrete transistors, because it was even done with vacuum tubes. But it would not be simple.

Up to the conversion of the RGB signals first to color-difference and then to Y, Pb and Pr, would be straightforward (relatively), but I see a real challenge in actually performing the quadrature chroma modulation.

Again, it can be done. Not simple, though.

There is an excellent book on all the requirements: "Video Demystified" by Keith Jack.
Get yourself a copy, and pore over all the intimate details.

You cannot convert RGB signals to Composite Video in a easy way.
Even-tough summing and scaling chroma signals will not work because synchronization signals should also be added.
Not easy..