I am having the same difficulty now. Did any ever find a solution.

A good place to find a very sweet script for doing a emerge -e world

http://forums.gentoo.org/viewtopic-t-494331.html

Bri

In order to make this useful changing from CHOST=i386 to CHOST=i686 remember to update your make.profile so that it is no longer pointing to no-nptl.

http://www.gentoo.org/doc/en/gentoo-upgrading.xml

Bri