test.js

page = require("webpage").create()

page.open("http://www.jonathanleighton.com", function() {
  var date = new Date()
  date.setTime(date.getTime() + 100000000)
  date = date.toUTCString()

  phantom.addCookie({
    name: "omg",
    value: "lol",
    domain: "www.jonathanleighton.com",
    expires: date
  })

  cookie = page.cookies[0]
  for (var k in cookie) {
    console.log(k + ": " + cookie[k])
  }

  phantom.exit()
})