If you were already confident enough to open up your PS2 for the swap trick or to mod your PS2, you should have no problem performing this fairly easy procedure. Of course, I will take no responsibility for any damage that might result from this procedure.
* Open up the PS2 unit, also remove the bottom casing and the metal shielding from the mainboard.
* Locate and remove the DVD drive's ribbon cable from the mainboard. It's easy, just click the connector's black strip away from the board and it slides out.
* Not only remove the cover and white disc from the DVD drive, but also unscrew the whole drive unit itself from the PS2 and take it out.
* Turn the PS2 upside down with its power connector and AV Multi Out facing you.
* Get a Neo Geo cartridge box (or something else about 1 inch thick). Use it to put on the DVD drive and connect the ribbon cable back to the mainboard.
* Get an item like your mousepad (or anything else NOT metallic or electrically conducting in any way with roughly the same dimensions as the mainboard). Put it on the PS2's mainboard and flip the DVD drive over on the mainboard with the ribbon cable still connected.
* If the downside of the laser unit itself is not visible, simply turning on the PS2 for a few seconds will make it slide to the center. Remember to shut the PS2 down again before progressing further!
Now that you see the laser unit, located on the top-right side of it are two small silver screw like components. These are adjustable resistors which you can use to adjust the properties of the lens.
Note very precisely in which direction they are both facing before doing anything, so you can always restore the original situation.