Kontakt version 1.2 or later provides AKAI batch conversion which can be accessed via the "Tools" button.

Tip:
In Kontakt options you should uncheck the option "combine AKAI / SF 2 samples to stereo" in order to prevent problems when loading loops with different loop settings for left/right. This uses to happen with AKAI instruments from time to time and causes an error while importing AKAI if the option is selected.