How do I make callback chaining/injection happen in a cleaner/testable way?

gistfile1.js

var
  http = require('http'),
  async = require('async'),

  printIP = function(cbs, data) {
    console.log("Your IP address: " + data.ip);
  },
  yellIP = function(cbs, data) {
    console.log("OI!!!  IP!!!  " + data.ip);
  },
  parseJSON = function(cbs, string) {
    cbs.shift()(cbs, JSON.parse(string));
  },
  getIP = function(cbs) {
    http.get({
      host: 'ip.jsontest.com',
      path: '/'
    }, function(res) {
      var str = '';
      res.on('data', function(chunk) {
        str += chunk;
      });
      return res.on('end', function() {
        // Shift the first callback off and call it
        cbs.shift()(cbs, str);
      });
    });
  };

// Pass in chain of callbacks.
getIP([
  parseJSON,
  printIP
]);

// Different one!
getIP([
  parseJSON,
  yellIP,
]);
// Prints, but if I wanted to return the IP address from this, how could I?