gistfile1.rbx

require 'rubygems'
require 'rubygems/package'
    def write_package
      open "/tmp/blah.rn", 'wb' do |io|
        Gem::Package.open io, 'w'  do |pkg|
          #pkg.metadata = @spec.to_yaml
          Dir["**/*"].each do |file| 
            next if File.directory? file

            stat = File.stat file
            mode = stat.mode & 0777
            size = stat.size

            pkg.add_file_simple file, mode, size do |tar_io|
              tar_io.write open(file, "rb") { |f| f.read }
            end
          end
        end
      end
    end

write_package