capmon.js

#!/usr/bin/env node
var zombie = require('zombie'),

    argv = process.argv.slice(2), // get rid of the leading "node" arg
    user = argv[0],
    pass = argv[1];

zombie.visit('https://login.comcast.net/login?continue=https%3A%2F%2Fcustomer.comcast.com%2FSecure%2FUsers.aspx', {
  debug: true,
  userAgent: 'Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2) Gecko/20100115 Firefox/3.6'
}, function (err, browser) {
  if (err) { return error(err); }

  browser
    .fill('#user', user)
    .fill('#passwd', pass)
    .pressButton('#sign_in', function (err, browser) {
      if (err) { return error(err); }
      console.log(browser.text('.usage-graph-legend'));
    });
});

function error(message) {
  process.stderr.write(message.toString() + '\n');
}