I'm with Mark on this one...Crosspicking on guitar as I know it is not changing pick direction in the "normal" fashion. To wit, "normal" would be down-up-down-up etc., and crosspicking would be playing ascending or descending courses as down-down-down or up-etc. A great example of this is Steve Kaufmann's version of "Wheel Hoss", in the second run through the tune. When done correctly, crosspicking produces some amazing tones.