Yeah, Folklord and Vox are right. The L3 and R3 buttons have no effect on how the analog stick functions for movement, they are just small tact switches stuck on the side which are closed when the analog stick is pressed in. You can ignore them or wire them for whatever functions you want, (R3 makes a good Home button).
I labeled the L3 and R3 points in the diagrams as just another reference point to relate them to the photo, and also to differentiate them from the ground pins directly below. Sorry if this was confusing, maybe I should go back back and edit that one.