At trailforums.com, there is a forum for the Continental Divide Trail. If you don't already have your answer, i'd try there.
I don't doubt Adam's answer at all, but it's weird to me that my trail map for the winds doesn't refer to the CDT, either for the Highline or any other trail. I guess that's the "flavor" of the CDT, as opposed to the PCT or AT...less official, less worn, you're more on your own.
Planning on hiking the whole thing Olivier??? It's too easy for you, i think. I think you should walk across from your home on the American Discovery Trail first, and THEN link up with the CDT en route to Gannett.
The last few hundred feet up the Green River route to Gannett?
That depends on how comfortable you are with steep rock. When Tom and I climbed it in 1990, we never took the rope out of our pack. But it is quite exposed. Those less comfortable would want to belay. Seems a pity to pack a coil of rope all that way and not use it, but if you need it.....
There is a lot of scree getting up to the col on the continental divide, but the final ridge to the summit is solid rock with good handholds. I'm not much good at ratings, and it was a long time ago, but I would rate the final 200 ft up the ridge as maybe 5.5 YDS.
If you want to discuss further, email me at firstname.lastname@example.org (new address).
I've been on Class 3s and a couple short class 4s, and i have a hard time imagining 5.5. That must be like overhanging rock that is smooth as glass, with flying monkeys chewing on your ears, right? Or is that 5.4?
YDS stands for "Yosemite Decimal System," and is a classification for rock climbing. 5.5 YDS corresponds to 4+ SCA. I think it's either 4 or 4+. Something else to relate to: I think the final ridge up Gannett is no harder than the summit knob of Granite Peak, MT. We took rope for both Gannett and Granite, but never took it out for either one. The north ridge of Gannett is, if anything, a little easier than MT.