I don't understand the first reference you gave in your original post, and I'm not totally sure about the second - but this last one isn't a material room procedure at all, assuming I have understood that as well as I imagine I have. I think I've also seen it proposed by Anton Kisiel back in the day.

I'd paraphrase it this way: take a plane on which you apply the source map. Then you morph the plane (insert handwaving here) until it has the UV mapping of the target. Then you render it in such a way that the input pixel values are exactly reproduced, which odf's method will do.

There are limitations to the transforms you can do this way, of course. You couldn't transform a V3 map into a V4 one, for example. Your plane would need to be high poly, i think. Also the process of deciding how to calculate the morph escapes me for all cases, although I did once make a prop which transforms a rectangular map into a circular one. The details were posted in the DAZ forum and are probably long gone by now.

Lastly, there's a little-known utility called UV2UV which can do this, albeit with some caveats, the major one being that the source and target meshes have to be the same. They also have to be triangulated, and the input and output maps have to be in BMP format; but those things are surmountable. Although I can't link to UV2UV it should be the top result if you search for it.