Some blockexplorer or something?
If you are 100% positive you know what pub/priv key pair the LTC existed "at" on May 12th of last year, and understand "change" addresses - the methods listed so far would likely be the easiest most sure-fire way to claim.
If you, however, don't understand "change" addresses, it is recommended you use the official CLAM software to claim.
EDIT:
The important point is that simply looking at your "receive" addresses in the GUI of a wallet will not guarantee that you get all of the CLAM you deserve.
This seems to contradict the claim in your sig that everyone who has LTC has CLAMs, despite your casino manager's spirited and emotional objections.