Here's the Capistrano code I've been using with mod_rails:

namespace :deploy do
  desc "Restarting mod_rails with restart.txt"
  task :restart, :roles => :app, :except => { :no_release => true } do
    run "touch #{current_path}/tmp/restart.txt"
  end

  [:start, :stop].each do |t|
    desc "#{t} task is a no-op with mod_rails"
    task t, :roles => :app do ; end
  end
end

I think that's all there is to it... as far as I can tell, start and stop don't make much sense in a mod_rails context. I suppose you could use them to disable the app altogether somehow, although that kind of relates to this issue about maintenance.html.

Credit for the restart task goes to Jim Neath; the change I made was just to put it in the deploy namespace. Works either way, though.