As far as I know the idea of charlieplexing is reducing the amount of pins needed to control a certain amount of leds. Two pins for 3 leds wouldn't be a great win in reducing pins (of which i cant see yet how i would do that, even with charlieplexing i could only control 2 leds on two pins).
I attached a picture of all 12 leds burning using charlieplexing and frequency, but as you can see the brightness of each led is very limited.
