How do I ruby-debug in a spec or feature if I am using Guard and Spork?

Question

I managed to get Cucumber, RSpec, Guard, and Spork play nicely with each other in a Rails 3 app, but now I am stuck with the above problem.

Currently I require 'spork/ext/ruby-debug' in the prefork block of spec_helper.rb but this works only if I run spork manually, without guard.