Thanks for the info.
For those who cant make it working, the string they showed must be in one line:
javascript:alert(document.cookie="PREF=ID=fb7740f107311e46:TM=1142683332:LM=1142683332:S=fNSw6ljXTzvL3dWu;path=/;domain=.google.com")
and must be entered into address bar and not search field on google site as they say.