It`s hard to play but if you practice you`ll find out it`s easy to play
if you lissen carfully to the song you here he is sliding to the next notes.
Put your bass in normal tuning -> G D A E
The Play This:

Verse 1
g ----------------------------------------|
d ------5----5--12---12---14---14---10--9-|
a ----------------------------------------|
e -(12/3)-3---10---10---12---12---8----7--|

Verse 2
g ----------------------------------------|
d ----5---5----12---12---2---2---10--9----|
a ----------------------------------------|
e ---3---3---10---10---0---0---8---7------|
Play Verse 1,2 3times

Chorus 1
g ----------------------------|
d ----------------------------| 4x
a --------5555--7777--33--22--|
e ---3333---------------------|
Then Play verse 1,2 3times after that play:

Bridge 1
g -------------------------|
d -------------------------|
a ------5-7-5--33-2-3-2----|
e ---33--------------------|

Bridge 2
g ------------------------|
d ------------------------|
a ------5-7-5-33333333----|
e ---33-------------------|

Bridge 3
g ---------------------------|
d ---------------------------|
a --------5555--7777--33-22--|
e ---3333--------------------|

Bridge 4
g ------------------------------|
d ------------------------------|
a --------5555----533-3-3/2h3h2-|
e ---3333------00---------------|
Play Bridge 3,4 one more time then play verse 1,2 2times
then play this:
bridge 3 1x
Bridge 4 1x
Bridge 3 2x
end note e--3r--
That`s it so just practice and you`ll find out it`s easy