this is the main riff
g|                           |
d|                           |
a|       _____               |       _____
e| 3 3 0 3 3 3 0 3 3 0 3 3 0 | 3 3 0 3 3 3 0 3 3 0 3 3 0

the bar over the 3's means it's a triplet

then the riff moves up a step

g|                          |
d|                          |
a|       _____              |
e| 5 5 2 5 5 5 2 5 5 2 5 5 2|

then it goes back to the main riff for a bar

this is that other part

g
d
a
e 5 5 5 7 7 5 3 3 0

there's a free part in E minor in the middle of the song

then one more run throught the riff and then

g
d
a
e 0 2 3          0 2 3
repeated for a few times

and be careful of that part where it stops (looking so good I just 
couldn't let her go) cuz it just picks up in the middle of the riff.

and the songs ends on G over and over

g
d
a
e 3 3 3 3 3 3 3

the aerosmith version is a bit different, as far as I can remember, my 
version has half studio, half live and i'm not sure if it's the one from 
the album.

g
d
a
e 3  3 0 3 3 0 3

etcetera

g
d
a
e 5 7 5 3 0

the part they add is something like this:

g
d
a                          2 3 5 3 2 
e 0 0  0 2 3  0 0  0 2 3 5           5 3 2

but i can hardly play it, so just play something similar

then after a few more riffs, it switches over to a live version which 
remains close to the original.