Scissors and some elbow grease, and it is fairly obvious. IMO, not worth the time or the money involved, though if you must get a cheap, easily accessible triple flanges for your E3s, well, whatever floats your boat.
This mod can be done on the Plugs as well, and it hardly improves it.
sound reminds me of the regular triflanges, slightly attenuated highs, with slightly better lows. They have really good isolation, and are comfortable, unlike the regular tri flanges (im my experience).
I did this mod on my e2c's, and didn't like the result. Initially the seal is good and it sounds great, but after a couple of hours, they make your ears really sore and make pretty deep grooves in your ears.