To create a new cookie, we can grab the cookie manager nsiCookieManager2 and use add():
var cookieManager = Components.classes["@mozilla.org/cookiemanager;1"]. getService(Components.interfaces.nsICookieManager2); var d = new Date(); cookieManager.add(".amazon.com", "/", "dmusic_download_manager_enabled", "on", false, false, false, ((d.getTime()-d.getMilliseconds())/1000) + 314496000);