How do you change odometer numbers?

A while back I purchased a used 69 instrument cluster to use for spare parts. (Wiper switch, headlight switch, speedometer, etc.). I need to change the speedometer cable hookup on the back of the speedometer currently on the car because the end housing is cracked and the speedometer cable won't attach. I have taken the odometer/ speedometer assembly out of the backup and want to install it in the car. While doing this I want to set the odometer miles to reflect the actual miles on the completed car rebuild. I have the odometer piece out and can't figure out how to set the numbers. I can get the numbers lined up but how do you set them before installing it back in place on the speedometer. This is a 1969 Plymouth Valiant which has been completely rebuilt...I want the odometer to reflect the miles since installing a new motor, trans, brakes, etc. Any help would be greatly appreciated. Thanks!