The Gentoo portage tree has JRE / JDK ebuilds for Java 8 (virtual/jdk and virtual/jre are currently hardmasked, but the oracle jre and jdk are currently in ~amd64)
I have an application that I develop and maintain on my Funtoo system that I will need to migrate to Java 8 soon - having Java 8 support in my Funtoo system is greatly desired. I would be willing to assist with any and all steps of getting the necessary components into Funtoo.