It is very straight forward to use:

In your model declaration:

class Customer < ActiveRecord::Base
  acts_as_convertible_to_csv :header => true, 
                             :fields => %w(id firstname lastname email_address)
end

Getting the csv data from a collection of records:

Customer.find(:all).to_csv

You can pass a block:

Customer.find(:all).to_csv do |line|
  # do something with each line
end

You can also convert individual records to csv:

Customer.find(:first).to_csv