I use Studio 6 because is powerfull and permits to do many things.
Of course now it's difficult to import the Arduino's library on studio6 and for me It could be nice if Atmel and Massimo Benzi work toghether to have compatibility with Studio 6 and Arduino's library.
It's my dream
Sorry for my personal opinion.
For answer at your question, import Atmel ASF in Arduino IDE I don't know well how to do. I don't think there will be much work to do, the project ASF is all in one folder with all that it need. (I think
Next days i'll try to do this. Time permitting.