Why not install the official package?? Otherwise if wanting to do using the sources from Ubuntu then you need to have a line starting with deb-src in your /etc/apt/sources.list like this below matching where you get your binaries from.
Code:
## Testing sources
deb http://ftp2.de.debian.org/debian/ testing main contrib non-free
deb-src http://ftp2.de.debian.org/debian/ testing main contrib non-free
Once you have done this then apt-get update or aptitude update now.
Code:
mkdir ~/temp
cd ~/temp
apt-get source fakeroot
cd fakeroot-???
sudo apt-get build-dep fakeroot
sudo dpkg-buildpackage -us -uc
Then install the resulting .deb file, I don't think I have left anything out but if you get any errors cut'n'paste them here so we can see them.