Yes, the 'Macrocom Method' section shows how it's done over the RGBI output, as used in this demo - the sample artwork shown there is in fact a much earlier version of one of the still images in Area 5150. :-)

Although while working on this one, I couldn't help noticing that the IBM CGA (5153) monitor wasn't showing things quite as expected. That led me down another rabbit hole: https://int10h.org/blog/2022/06/ibm-5153-color-true-cga-pale...