The only tool you will need is another SAK, preferably a Victorinox, and preferably with the can opener. The broad flat blade of the can opener is ideal for getting under the scale and levering it off.
Step One: Remove the tweezers and toothpick from the “patient” in order to make a small opening to get the can opener into.
Step Two: Slide the can opener into the toothpick (or tweezer) slot and pop the scale off the first rivet.
Step Three: Slide the can opener down the length of the “patient” until the scale is separated from the knife.
Step Four: The scale should simply fall off the knife, and you are now ready for new scales.