Of the major CCRMA audio tools, Portage has two -- media-sound/snd and media-sound/cm. I would like to see the others added to media-sound or media-libs as appropriate: Common Lisp Music (clm) Common Music Notation (cmn) sndlib (audio libraries) STK (C++ signal processing toolkit)
please attempt and ebuild at http://www.gentoo.org/proj/en/devrel/handbook/handbook.xml?part=2&chap=1
Reopen if you have an ebuild. Meanwhile, marking LATER.