I used to do this for some customers at a custom lab in the eighties, as the older colour materials were, by then, showing considerable fade, but before computers, when film was still king. Conventional colour printing cannot correct for the fading, as the highlights need a different balance than the midtones, than the shadows. Based on some info I read off of a Kodak publication I worked out the details of a method to restore fade by making a duplicate trans, in contact, and registered with the original, that was missing the dye that had faded out through the ravages of time. The key is that the fade is porportional, in that for example, you will of lost say 50% of the cyan dye(the original would now look red), you would make a fog exposure with a strong cyan filter, then a second one with the original in contact, then process your dupe. When its' out, it would look very odd, but when placed back into contact, and registered with the original, then as if by magic it would look nearly normal, that is if you had all your exposures and filtration correct. One of the important tools that I had at my disposal was a densitometer, I would read a black area to get an idea of what had been lost, then base a series of test exposures on that.
One of the important things is the denisty of the original, the best were ones that were slightly underexposed, so that there was enough of detail left in the highlights. A thin trans wouldn't work as well, since there was minimal density in the highlights, to start with, and after a fair porportion of the dye was loss, then there wasn't much left to work with.
As a former dye transfer printer also, I'm sure that it could be done that way as well, probally very well although I am not familiar with this article, and did not try this when I was doing dye transfer.
The advent of computer processing, and tools such as Photoshop put an end to that type of work also!
Keith