By definition, no one wants to implement the CEV of humanity more than they want to implement their own CEV.
That depends. The more interconnected our lives become, the harder it gets to enhance the life of myself or my loved ones through highly localized improvements. Once you get up to a sufficiently high level (vaccination programs are an obvious example), helping yourself and your loved ones is easiest to accomplish by helping everyone all together, because of the ripple effects down to my loved ones' loved ones thus having an effect on my loved ones, whom I value unto themselves.
Favoring individual volition versus a group volition could be a matter of social-graph connectedness and weighting: it could be that for a sufficiently connected individual with sufficiently strong value-weight placed on social ties, that individual will feel better about sacrificing some personal preferences to admit their connections' values rather than simply subjecting their own close social connections to their personal volition.
Then they have an altruistic EV. That's allowed.
But as far as your preference goes, your EV >= any other CEV. It has to be that way, tautologically. Extrapolated Volition is defined as what you would choose to do in the counter-factual scenario where you have more intelligence, knowledge, etc than you do now.
If you're totally altruistic, it might be that your EV is the CEV of humanity, but that means that you have no preference, not that you prefer humanity's CEV over your own. Remember, all your preferences, including the moral and altruistic ones, are included in your EV.
There seems to be a widespread impression that the metaethics sequence was not very successful as an explanation of Eliezer Yudkowsky's views. It even says so on the wiki. And frankly, I'm puzzled by this... hence the "apparently" in this post's title. When I read the metaethics sequence, it seemed to make perfect sense to me. I can think of a couple things that may have made me different from the average OB/LW reader in this regard: