Ease requires the following packages (pkg-config names shown here):
With those installed, building should be a simple:
./configure
make
sudo make install
There is an Ubuntu PPA for Ease, currently with binaries for Ubuntu 10.04 "Lucid" and 10.10 "Maverick".
sudo add-apt-repository ppa:natesm/ease
sudo apt-get update
sudo apt-get install ease
If you'd like to see exactly what's going on, you can clone Ease from git:
git clone git://git.gnome.org/ease
To build Ease from git, you'll also need additional build tools, including the Vala compiler, which can be found in your package manager or as a tarball here.