The intro should be done using NATURAL HARMONICS like this..
|—-12—–5—————-12——5————————————–|
|-12——5—————12——-5—————————————-|
–12————————5———————————–|
—————————————————————-|
—————————————————————-|
—————————————————————-|
~~~~~~ ~~~~~~
~ pretty wild vibrato – since this is a harmonic on an open string you need
to use a vibrato arm (or if your guitar does not have one you can do this
by applying pressure to the string above the nut – but this is harder
to control)