I have an 1950’s home with older wiring. Most of the house only has a black and white wire connecting to lights and recepticals. I want to do a 3-wayswitch. Currently, the power is coming in through the light then connecting to the on/off switch. How could I install a 3-way if I can only add a new wired line from a new switch (#2) to the current light and also cannot upgrade or touch the existing wired line from the current switch to the current the current light? The reason I cannot touch the existing line is because it is behind 2x4s and walls where’d I have to demo a wall which is outside of my capabilities.