Can you not let a car register mileage by switching odometer miles to KM very rapidly?

I have new mercury and odometer could switch miles to metric with push of a on. If I could wire a relay or oscillator to that on that changes miles and km, really fast, can It prevent my sys from counting any miles? I dont know. I may remove on and solder contacts to an oscillator to "press" it many times a second. I know it may be illegal but is it possible? Car manual says cannot tamper w odo reading but can you switch units real fast? (Im a tech guy)