So humbling oneself and putting one's faith in God who did everything required is considered boasting?
Contradiction much?
You realize that when the verse says "lest any man should boast," it's not talking about boasting about Christ, right?
Because Paul says:
But God forbid that I should boast except in the cross of our Lord Jesus Christ, by whom the world has been crucified to me, and I to the world. - Galatians 6:14 http://www.biblegateway.com/passage/?search=Galatians6:14&version=NKJV
No rebel ever humbles himself. Humans are by nature prideful and selfish as they attempt to rule their own lives. Left to themselves (see Romans 1) they will attempt to place themselves on God's throne.
Ephesians 2:9 is referring to you boasting about how you conjured your own faith and chose God. You cannot do so because the very faith you have is because God made you alive in Christ.