To use the gem simply added the following to your Gemfile
The gem is still in alpha so expect the unexpected.
To setup stalking like functionality just add the following to your User model
include Stalker has_and_belongs_to_many :followers, :autosave => true, :dependent => true, :class_name => 'User', :inverse_of => :following has_and_belongs_to_many :following, :autosave => true, :dependent => true, :class_name => 'User', :inverse_of => :followers
Doing so will make your model a stalker :D
This project rocks and uses MIT-LICENSE.