If you have your funds in your own wallet then no need to do anything. Your share is generated from the balance in your wallet at a certain date, and you can use the keys to that wallet to claim your share later on.
If you have your funds in an exchange the matter is more complicated, as exchanges usually control the keys to the funds you hold there. Some exchanges claim your shares and give them to you, while others (e.g. Cryptsy) typically are unable or unwilling to do this for users.