How to use compass with rails 3.1

I have searched and searched and all I could see was that to use compass with rails 3.1 was to just edit the Gemfile like so:

gem 'compass', :git => 'https://github.com/chriseppstein/compass.git', :branch => 'rails31'
gem 'sass-rails', "~> 3.1.0.rc"

Yes I understand that but what next? Every tutorial I saw said just that, use that certain fork. But I am still having trouble with using compass with rails 3.1.

I did this:

$ compass init rails . --syntax sass
  directory ./app/stylesheets/ 
  create ./config/compass.rb 
  create ./app/stylesheets/screen.sass 
  create ./app/stylesheets/print.sass 
  create ./app/stylesheets/ie.sass

And since 3.1 was using assets now, I just transferred all those files to 3.1. Also, I am using compass-960 plugin, so where do I require it? I tried adding a compass.rb with require 960 and require html5-boilerplate and I still keep getting errors:

Error compiling asset application.css:
NoMethodError: undefined method `Error' for Compass:Module
  (in /Users/eumir/rails_apps/kiseki/app/assets/stylesheets/screen.sass)

NoMethodError (undefined method `Error' for Compass:Module
(in /Users/eumir/rails_apps/kiseki/app/assets/stylesheets/screen.sass)):

I tried doing compass compile and it gave me this:

$ compass compile Nothing to compile. If you're trying to start a new project, you have left off the directory argument. Run "compass -h" to get help.

As I said, I already edited my compass.rb so I am still stumped as to how to go about with this. Any help?

Solution

The solutions in the other answers are deprecated with the latest version of Compass, v0.12, which requires an adapter to work with a rails app. The Compass author, Chris Eppstein, has put installation instructions on github:
https://github.com/compass/compass-rails

This adapter supports rails versions 2.3 and greater