Dimming Indicator Lights separate from 12 volt switches

DIY
, ,
1

I want to dim an LED indicator bus light bus (8 lights) on the negative side with a Pwm dimmer. In other words, each switch activates its own light, but I want to dim those lights. Better way than negative side PWM dimming? How would I wire the bus after the switches, so I can dim all of them for a night marine application. Does a PWM work with negative side only? I realize the PWM has to be powered, but what happens to output positive + in this scenario?