I'm about to change out the instrument cluster on my 1999 C230 (the existing cluster has broken LCD segments). But, before I do this, does anyone know, how do I set the odometer reading on the replacement cluster to the right numbers?

I checked with a dealer and they say it can only be done by the factory. He said they have to set a serial number and the odometer reading. I guess the serial number comes from another computer on the car. And, the only way they can do all this is if I buy the cluster from them. Thanks for the help,
DonB