I won’t be of much help here but I think this is not the simplest of mods to get started with. These tiny leds are more sensitive to overheating than our main emitters, so it’s a good case for hot air, hotplate, or hot tweezers rather than an iron, but an iron used the right way is totally doable (and easier to solder on the new ones vs. removing the existing ones). Just be careful not to tear the pads on the board and paste flux will aid in both removal and install. The trim rings unscrew pretty easily so the pliers should work fine (might put some electrical tape over the tips or across the trim ring itself to help avoid scratching). I use internal snap ring pliers for them (the outward pressure helps keep them from slipping a little better than typical external pliers). Sometimes you can even get the ring started just with fingernails or finger pressure. When you put the ring back on, resist the urge to overtighten…snug against the rubber is usually fine. Also, not sure about this light in particular, but aux switch boards are often held in place by a tiny dot of glue, so you may need a small pick or something to pry it gently and break the glue.
Here’s Tom’s fantastic teardown photos…scroll down to the Driver section and he begins with the switch. Someone else will need to chime in on the size of those and if changing colors might require a chance in the teeny resistors to maintain the same brightness. It’s that way on most or all of the lighted tailswitch mods. Other than working with such tiny components (and locating/purchasing them) the good thing is that you can tailor it to exactly what you like. You might post in Tom’s thread and he’ll probably see it and give great input…maybe also search the past threads on lighted tailswitches where tech info/resistor details was shared.