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