I just got this to work.
First make sure that you don't have any emerald or libemeraldengine-dev package installed then:
mkdir emerald++
cd emerald++
git clone git://anongit.compiz.org/fusion/decorators/emerald
cd emerald/
git checkout -b compiz++ origin/compiz++
./autogen.sh --prefix /usr
make
sudo checkinstall
# version 0.9.4
sudo dpkg -i --force-all emerald_0.9.4-1_amd64.deb
extract
cd emerald-themes-0.6.0
./autogen.sh --prefix /usr
make
sudo checkinstall
Here are two amd64 packages that I built on oneiric
http://dl.dropbox.com/u/27872107/emerald-themes_0.6.0-1_amd64.deb http://dl.dropbox.com/u/27872107/emerald_0.9.4-1_amd64.deb