How can a 3-way switch with power at the light be properly installed in a circuit?

To properly install a 3-way switch with power at the light in a circuit, you need to connect the power source to the light fixture first. Then, run a 3-wire cable from the light to the first switch, and another 3-wire cable from the first switch to the second switch. Connect the wires according to the wiring diagram for a 3-way switch setup, making sure to follow proper safety precautions and turn off the power before working on the circuit.