Resque の Worker 毎に Redis のホストを設定する ref: http://qiita.com/eccyan/items/c10b4b0080c235b65976

worker.rb

require 'worker_base'

class Worker < WorkerBase
  @redis = OTHER_REDIS_HOST

  # ...
end

worker_base.rb

class WorkerBase
  def self.before_enqueue(*args)
    Resque.redis = @redis if @redis
  end

  def self.after_enqueue(*args)
    Resque.redis = DEFAULT_REDIS_HOST
  end
end