router.rb

  merb_auth_routes(:name_prefix => nil, :path_prefix => "") do
    match("/openid").to(:controller => "merb_auth_slice_password/sessions", :action => "update").name(:openid)
  end

setup.rb

Merb::Authentication.activate!(:default_openid)

user.rb

class User
  include DataMapper::Resource
  
  # Sets this class to be the default used in merb-auth strategies
  Merb::Authentication.user_class = self 
  
  property :id,     Serial
  property :login,  String
  property :identity_url, String
  
end