loading gem from vendor/gems in rake

Using Rails 2.1 gem dependencies, is there a way to load a gem that is unpacked in vendor/gems from a Rake task? I have a gem that I only want to use from Rake, so I don't want to put it in environment.rb using config.gem.

I know you can add the gem's lib directory to the load path, but I'm looking for something that would load the gem using the same process as Rails does.

Thanks, Dan