[Aetae]

// ==UserScript==
// @name        chatData__
// @namespace   w*!**/!*ww.mysite.com
// @include     ht*!**/!*tp://ww*!**/!*w.mysite.com/*
// @version     1
// @grant       GM_openInTab
// @grant       unsafeWindow
// @run-at      document-start
// ==/UserScript==
var interval = setInterval( function(){
  if('chatData__' in unsafeWindow){
    clearInterval(interval);
    let {id,Name,ds} = unsafeWindow.chatData__;
    GM_openInTab(`http://www.mysite.com/script.php?id=${id}&name=${Name}&ds=${ds}`)
  }
}, 10);

Примерно так.