Welcome to the multilib-overlay wiki!
This overlay replaces the binary emul-linux-x86-* packages from Gentoo portage with native compiled ones.
This is done with multilib-native.eclass that wraps all ebuild phase functions, and adds a lib32 useflag.
There are several ways to install the overlay
The simple way is to emerge the emul packages of the overlays and solve the dependencies for the lib32 useflag
For amd64 you may have to set SETARCH_ARCH_x86="i686" in /etc/make.conf
something similar may be needed for other arches too.
It must be a valid parameter for the setarch command
For help /join #gentoo-multilib-overlay @ freenode