I'll be anxious to see what gets posted here in response to GUEST,Andrew's question. I'm only familiar with the term crosspicking as applied to the flatpicking technique of the same name.

When I crosspick, using a flatpick, I am basically using a flatpick to mimic the three-finger roll that bluegrass banjo players use. If the term is being applied consistantly, I'm guessing that crosspicking fingerstyle might be a little like playing banjo rolls on a guitar.

Tommy Flint is the author of a great many books on fingerstyle guitar, many of them in the Chet Atkins style. Chet—like all the great thumbpickers—played a lot of fingerstyle licks that sound like crosspicking. Still, I'm guessing that most of the references you'll find to “crosspicking” will be flatpicking techniques.

      - Mark