How to use length of wire as "buttons"
As you might know, a "wire pot" has three terminals.  It has two ends, plus a "slider."
If you place a copper bead on the wire and tie the ends of the wire to some insulator, you will now have a "linear" potentiometer. 

Solder a wire to each end and the copper bead. Connect the wires to the corresponding terminals on the PCB, and you are "good to go."  

If you really meant "use your finger" as the slider, then you need a different (and more complex) circuit.  I would recommend using an "oscillator" and your hand would serve as the tuning capacitance.