I want to fit a total of three headlights on my average 220. What type of modifications do I need to make in the wiring to make it possible?
Do you have a Pulsar 220? If so, you probably don't want two full-blown headlights, if the electrical system on a 220 is anything like that of the 135LS. On my bike, the electricals can barely keep up with all the lights on, plus both signal lights blinking (unless I raise the idling speed).
You should probably look into adding accessory lights, instead. For example, I've managed to attach two cheap bullet LEDs (mounted on the forks) and they work well enough that I sometimes forget to turn on my headlight. Mounted in this manner, I've also managed to achieve a "triangle of light" that just might let me be a bit more visible to oncoming traffic.