I don't use Chrome (for some odd reason it just never seems to work right for me, regardless of what computer I use it on), but I
think it's called TamperMonkey.
I also think
most -- but not all -- GreaseMonkey scripts will work in TamperMonkey.
Actually, just go read this thread here, since it'll give you better answers than I can.
http://goallineblitz.com/game/forum_thread.pl?thread_id=4616946