Running this should only require Rails 2.2.2 or later, and the command line interfaces for sqlite3 and curl. Tested on Ubuntu Linux 9.04 (“Jaunty Jackalope”) and Mac OSX 10.5.6 (“Leopard”).

Installation of all necessary dependencies from a fresh install of Ubuntu 9.04:

sudo apt-get install rails git-core sqlite3 curl
sudo gem install rubygems-update
sudo /var/lib/gems/1.8/bin/update_rubygems
sudo gem install rails
sudo gem sources -a
sudo gem install rubys-gorp

Execution instructions:

This is a library which, among other things, will interpret ARGV.  Here's
an example based on

ruby makedepot.rb [VERSION] [--bundle] [--restore] [RANGE]... [--save]

  "VERSION" - specifies the Rails version to test.  Examples:

  "--bundle" - bundle this version of rails with each Rails app generated.
    - if libraries are listed in the RUBYLIB environment variable, they
      will be added as directories to the Gemfile before making the bundle
      (adding '--system' will only bundle system gems)

  "--restore" - restore from snapshot before resuming execution

  "RANGE"   - specifies a set of sections to execute.  Examples:

  "--save"  - save snapshot after execution completes

  "--rails-debug" - turn on BACKTRACE and Thread.abort_on_exception

Tests against the output produced (e.g., makedepot.html) can also be run separately:

ruby checkdepot.rb [partial]

"partial" means that tests which cover sections that are not included in
  makedepot.html are to be omitted.