Getting RubyGems to work with JRuby

I'm sorry if the title gives it away, but here are some recent output in my terminal window:

#bin/jruby bin/gem install rails --include-dependencies
Attempting local installation of 'rails'
Local gem file not found: rails*.gem
Attempting remote installation of 'rails'
Updating Gem source index for: http://gems.rubyforge.org
Successfully installed rails-1.1.2
Successfully installed activesupport-1.3.1
Successfully installed activerecord-1.14.2
Successfully installed actionpack-1.12.1
Successfully installed actionmailer-1.2.1
Successfully installed actionwebservice-1.1.2
Installing RDoc documentation for activesupport-1.3.1...
Installing RDoc documentation for activerecord-1.14.2...
Installing RDoc documentation for actionpack-1.12.1...
Installing RDoc documentation for actionmailer-1.2.1...
Installing RDoc documentation for actionwebservice-1.1.2...

So, we have RubyGems mostly working. Right now there are two caveats. First, during the YAML parsing, we get some InterruptedExceptions for some reason. This doesn't seem to impair functionality, though. The second problem is that it takes serious time. Between 30 minutes and an hour for this. The two parts that are time hogs are the YAML parsing of the Gemspec, and the RDoc stuff, for some reason.

So, what do you need to do, to get this working?

• Start from a newly checked out JRuby.
• Add patch for RubyTime and TimeMetaClass. (Adds gmt_offset and utc_offset. This patch can be found in the jruby-devel archives.)
• Checkout the latest version of RbYAML from RubyForge, and put this in $JRUBY_HOME/lib/ruby/site_ruby/1.8.
• Add the contents from the C Ruby libraries.
• Change fileutils.rb, so that RUBY_PLATFORM works.
  
• Replace the file $JRUBY_HOME/src/builtin/yaml.rb with the yaml.rb for RbYAML, that can be found here.
• Change the jruby and jirb scripts by adding -Xmx512M. (I'm not sure 512 is really needed, actually. Maybe 256 or 128 suffices.)

And this should be everything that's needed to get the same results as me when trying to install Rails (provided you've got the patience).