Is it possible to install Gentoo portage manager (emerge) on Ubuntu?
You might be interested in Gentoo Prefix.
Usually, Gentoo's Portage installs in the root of the filesystem hierarchy, '/'. On systems other than Gentoo Linux, this usually results in problems, due to conflicts of software packages, unless the OS is adapted like Gentoo/FreeBSD. Instead, Gentoo Prefix installs with an offset, allowing to install in another location in the filesystem hierarchy, hence avoiding conflicts. Next to this offset, Gentoo Prefix runs unprivileged, meaning no root user or rights are required to use it.