Currently we don’t provide any binary packages, so you must build it
on your own. Although the package is suitable for using with debian
stables [= squeeze at the time we wrote this] building it depends on
packages only found on experimental branch: ghc and
cabal-install.
If you can workaround these, building it should be fairly straightforward:
$ git clone git://github.com/locaweb/leela.git
$ cd leela
$ debuild
After that you can install it using dpkg:
$ sudo dpkg -i ../leela_<version>_<arch>.deb
$ sudo apt-get -f install