Playstation 2 Disk Swap Mod
Unfortunately, because of the mechanics of the playstation 2, there is no way to modify your playstation once, put it back together, and disk swap forever. To disk swap, your playstation 2 must be pulled apart.

Step 1: Break your warrenty sticker. (This will void your warrenty, but it should be over by now anyway)
Step 2: On the bottom of the ps2, there are 8 screws. undo these (there are 2 that are hard to see). These screws are hidden by rubber or plastic squares - these just pop off with the help of a knife or screwdriver.
Step 3: Carefully take off the top of the ps2. DO NOT use brute force - the power and reset buttons are connected to the top and there is a fragile ribbon cable attached to the base.
Step 4: You will see something like this
Take out the four screws as shown and lift off the black tray.
Step 5: Clipped to the top of the black tray is a magnetic white disk. Unclip this, you will need it to disk swap.

Thats it. Everything else you need to know to played copied games is explained in the PS2 disk swapping guide.