Can i use a 10k OHM preset potentiometer?The scale probably use load cells to determine the weight. These cells will probably be configured in a "bridge" configuration and the output of this bridge will be fed in an amplifier (most likely the square integrated circuit). The output of this amplifier will be used to determine the weight of the person standing on it.
If you were to modify this circuit I would probably find the output of this amplifier and hijack it and provide your own voltage. As in the example shown below. Here I added a potentiometer, but you could also provide your own circuit.
Hope this gets you going, good luck!
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