The chrony ebuild just needs a version bump to 1.20. Everything works fine but you need 1.20 to make chrony work with kernel 2.6.
Chrony 1.20 has been working successfully on my system for a few months now too. I suggest marking it as stable for x86.
Chrony-1.20 is in portage, keyworded ~x86 - changing summary to stable request.
Marked stable for x86. David, Ilya, please check if it can be marked stable for your arches.
Closing this bug since nobody seems interested in enabling chrony on other platforms. Although if you feel like it, try out 1.20-r1...