This gem should work out of the box. All you have to do is add the gem to your Gemfile:
Then bundle install or update (depending on if you want to upgrade an older version of this gem).
bundle install bundle update
//= require jquery . . //= require d3
Version numbers of this gem have been changed as of 2-2-2012 to reflect the d3 version numbers.
As of version 3.0.0, the extraneous files from legacy version of d3 have been removed.