Initialize DataMapper connections in different classes

gistfile1.txt

class RssSqliteModel
  def initialize(path)
    # logs display
    DataMapper::Logger.new($stdout, :debug)
    DataMapper.setup(:default, "sqlite://#{path}")
    DataMapper.finalize
    DataMapper.auto_migrate!
  end
end

Let's assume we have a script that either initializes a postgresql or a sqlite connection by using the same model as in https://gist.github.com/943379: where exactly may the model be placed and the initialization to RssSqliteModel be called ?