ebuild:

cat flvtool2-1.0.6.ebuild
# Copyright 1999-2006 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
# $Header: $

MY_P=${PN}_${PV}

DESCRIPTION="Flash video and meta data manipulation"
HOMEPAGE="http://www.inlet-media.de/flvtool2"
SRC_URI="http://rubyforge.org/frs/download.php/9225/${MY_P}.tgz"

LICENSE="BSD"
SLOT="0"
KEYWORDS="~x86"
IUSE=""

S=${WORKDIR}/${MY_P}

DEPEND="virtual/ruby"

src_compile() {
        ruby setup.rb config || die "setup.rb config failed"
        ruby setup.rb setup || die "setup.rb setup failed"
}

src_install() {
        ruby setup.rb config --prefix=${D}/usr --siterubyver=${D}/usr/lib/ruby/site_ruby/1.8 || die "setup.rb config failed"
        ruby setup.rb install || die "setup.rb install failed"
        dodoc CHANGELOG README
}


error:

>>> Emerging (1 of 1) media-video/flvtool2-1.0.6 to /
 * flvtool2_1.0.6.tgz MD5 ;-) ...                                                                                                                               [ ok ]
 * flvtool2_1.0.6.tgz RMD160 ;-) ...                                                                                                                            [ ok ]
 * flvtool2_1.0.6.tgz SHA1 ;-) ...                                                                                                                              [ ok ]
 * flvtool2_1.0.6.tgz SHA256 ;-) ...                                                                                                                            [ ok ]
 * flvtool2_1.0.6.tgz size ;-) ...                                                                                                                              [ ok ]
>>> Creating Manifest for /usr/local/portage-overlays/personal/media-video/flvtool2
 * checking ebuild checksums ;-) ...                                                                                                                            [ ok ]
 * checking auxfile checksums ;-) ...                                                                                                                           [ ok ]
 * checking miscfile checksums ;-) ...                                                                                                                          [ ok ]
 * checking flvtool2_1.0.6.tgz ;-) ...                                                                                                                          [ ok ]
>>> Unpacking source...
>>> Unpacking flvtool2_1.0.6.tgz to /tmp/PORTAGE/var-tmp/portage/media-video/flvtool2-1.0.6/work

!!! ERROR: media-video/flvtool2-1.0.6 failed.
Call stack:
  ebuild.sh, line 1614:   Called dyn_unpack
  ebuild.sh, line 751:   Called qa_call 'src_unpack'
  environment, line 1246:   Called src_unpack
  ebuild.sh, line 637:   Called unpack 'flvtool2_1.0.6.tgz'
  ebuild.sh, line 404:   Called die

!!! flvtool2_1.0.6.tgz does not exist
!!! If you need support, post the topmost build error, and the call stack if relevant.
!!! A complete build log is located at '/tmp/PORTAGE/var-tmp/portage/media-video/flvtool2-1.0.6/temp/build.log'.

!!! This ebuild is from an overlay: '/usr/local/portage-overlays/personal'