Ubuntu, like its parent Debian, use DEB packages. These are entirely different than what Sabayon and its parent Gentoo use. For one thing, Gentoo and Debian are like apples and oranges and they are not compatible with each other. In Gentoo, the package manager portage is similar to BSD's ports system; all packages and their dependencies are compiled from source tarballs as they're installed. Sabayon makes things easier by per-compiling packages into usable binaries which are installed quickly and easily with entropy. There is no way you will be able to gerrymander Sabayon/Gentoo to use an Ubuntu PPA for packages. Sorry! You can, however, fetch any packages source tarball and compile it into a binary yourself. Do some research on this and see how you'd go about doing it.
AMD Phenom II 64 X6 1090T Black Edition
8192 MB DDR2 RAM
nVidia Quadro 600 w 1024 MB DDR3
Sabayon 13.x 64 Bit KDE, (Limbo enabled)
"Better to remain silent and be thought a fool than to speak out and remove all doubt." -- Abraham Lincoln