I didnt even try to replace those but here is a procedure I found over at DT:
The procedure for both the 4x4 switch and headlight switch is very similar. Remove both of these from the dash and bring them to the bench. You'll need a electronics vise and good soldering iron for this part. First, remove the screws from the back side of the module. Then holding it with the buttons/knob facing down, remove the back of the assembly. You'll be left with the back half of the assembly with the circuit board in it all full of dielectric grease. On both modules you'll see a small bulb in a square white housing. This is the point of no return! Grab the white part with a pair of pliers and gently rock it back and forth until it breaks free. This will leave you with two solder pads underneath where the bulb housing was. I used WLED-X leds for this part. You need to remove the LED, resistor, and diode from the base. You'll take this WLED bulb and straighten the leads out. Then using a pair of pliers, gently squeeze the base where it meets the LED itself. Do this a few times, from all sides, and it'll break the glue holding it together. Then you can grab the LED and pull it straight out of the base. Leave the resistor and diode attached to the LED, but trim the leads to about 3/16". bend the remaining tails 90 degrees toward each side. you'll solder these tails to the pads on the PCB that you exposed earlier from under the old lamp housing. Polarity does matter. I can't remember which way each was supposed to be. If you get it backwards, just pull it back apart and reverse the contacts.
The WLED-X bulb he is talking about is also from superbrightleds.com