Palms Out pullups still use biceps to some degree, but the mechanics of the position make it much more of a lat workout. Palms In is the opposite, mostly biceps, a little bit of lats.
I know that from personal experience, but I also have a source: Bodybuilding.com maybe isn't definitive, but it is full of guys who know exercises. Pullups. and Chin-Ups.
I know that. I was just saying you can't totally cut out the biceps. The reason for less bicep usage on the palms-out method is that your wrists are twisted in such a way as to negate much of the biceps lifting power and they can't contract with the same amount of force as efficiently.
Raczak, how do you like cross-fit? I've heard many positive reviews.