haha, I had the same problem. you just have to lift the tongue up and use your thumbs to pull the metal things apart (they are L shaped so just pull one side out and the other will come out easily).
I didn't sand them, and it depends on how dark you want them (the "black" was in there for over an hour and it's still kinda purple), just keep checking them and when you see them the way you want them take 'em out.
at least they offer tongues, unlike dalbello where it's an ordeal to get replacement tongues
apparently there's an A tongue in production that's stiffer than the B which is the stiff tongue for the krypton pro...i really wanna get my hands on that
it'll make the k pro's like a 150 flex with that tongue plus the high setting flex wedge mod