Gemfile.rb

source :rubygems

# load WatirSplash and it's dependencies
gem "watirsplash", "2.1.1"

platforms :mingw, :mswin do
    gem "watir", "2.0.1"
    gem "win32screenshot", "~>1.0.5", :require => "win32/screenshot"
end

gem "watir-webdriver", "~>0.3.1"
gem "firewatir", ">= 1.9.3"
gem "rspec", "~>2.6.0"
gem "spork", "~>0.9.0.rc9"

# add your project specific dependencies here:
# gem "ruby-debug", "0.10.3"

gemspec.rb

Gem::Specification.new do |s|
  # ...  
  s.add_dependency("rake", "0.8.7")
  s.add_dependency("require_all")
  s.add_dependency("syntax")
end

load_watir.rb

begin
  gem "watir", "=2.0.1"
  require "watir"
rescue Gem::LoadError
  puts "\nWatir dependency is missing. Install it with:"
  puts "  gem install watir -v 2.0.1"
  exit 1
end