ive seen them done...but how??? links, tips, any help would be appreciated. thanks
Quote by Wrst_Plyr_Evr
do it just as it sounds. I hate to be cliche but it's all in the wrist.

ok...but do my fingers do anything special?
Fret the 3rd fret and tap the 15th fret (octave, 12 frets up) right on the bar with your middle or index finger. You can do any fret and tap 12 frets higher. Nothing special really with the right or left hand, just practice tapping it and listen well because on an acoustic they won't be that loud.