First off, install cuetools & shntool via your package manager.  cuetag is not part of the gentoo portage package.

Cuetag pop this in /usr/bin/  <-- taken from the source from berlios.de

Cuesplit pop this in /usr/bin/ <-- adapted from archlinux forum

Obviously you will need the libraries for your media ie flac, mac, shn, wavpak etc.

Useage: cd into the directory of the audio image and run cuespilt.  Done. :)