If you replace the gauge cluster...
 

Say for whatever reason, you buy another gauge cluster...

... the odometer reading will be set to the previous car's mileage, correct? How does one go about changing it to match your car's actual mileage?

Correct, to reset the mileage to your correct mileage, you have to goto the dealer for that but i hear that they will do that only on new clusters, not used.

I asked this same question. They told me you have to bring it to the dealership to have it reprogramed. Not sure of the cost. Thumper may know, as he just had his done with his car.

One a cluster has 62 or more miles it is locked and a dealer cannot chage it. But there are aftermarket companies that can.

Just as Tool Pants said, I did this with my SUV. I did a popular gauge cluster switch and went to a aftermarket company.

By our State Law the vehicle is required to carry an attached sticker that the cluster had been changed and the mileage in fact is verified by the installer and correct for the car.

Even though they had to do the install, it wasn't bad, about $75.