You can either download it as a gem,
or if you have the gem system installed :
gem install openwferu
and use it from within your ruby code
require "rubygems"
require "openwferu"
#...If you want it fresh from the source, check out the source by running
git clone git://github.com/jmettraux/ruote.git
and then run
cd ruote rake gem
to build the latest gem with the latest source.
(“ruote” is the nickname of the workflow engine itself).
You can run the unit tests with
rake qtest
(more about unit tests in the devdoc)
More info in the README.txt coming with OpenWFEru.