config = {
  "default" => "localhost:6379",
  "a_queue_of_write_heavy_stuff" => "otherbox:6379"
}

Resque.redis = Resque::RedisComposite.new(config)
Resque.push("email_sending", "to" => "dave@example.com") # to localhost:6379
Resque.push("a_queue_of_write_heavy_stuff", 23239430449) # to otherbox:6379

# Get it?