You can still get OEM ones, but they're going to be used. You can get Replica OEM Ones made of Fiberglass that are new. If my memory server correctly, to take off the Stock Rocker Panels, you do this:

-Take out some clips (Probably 3 or 4) that are on the bottom underneath the car
-There might be a screw or two that hold on the rocker panel inside the front wheel well, take them out if there are any.
-Then Pop the rocker panel from the rear wheel well towards the front, it'll slide off.
-Take off the little clips that are still on the car and put them in the new rocker panels.
-Simply Pop on the new ones straight onto the car, put in the clips on the bottom and the one or two screws (if there were any).

I hope that helped some.