Alright so once again, figured this out by watching Jonny play it live. I was under the impression that it was played on 3 different strings (with the Ebow of course) but that is not the case. The whole riff is played on the G string with a couple hammer-ons, pull-offs, and slides because hooray for sliding up and down strings for cool sounds!! It's actually pretty easy though so that's a good thing.

 

Note: If you don't have an Ebow, which fortunately I do, you can still play this riff by tremolo picking, but it just won't sound so 'authentic' unless you could actually tremolo pick quickly and softly enough so that you can't even hear the pick attack on the strings... Along with the long drawn out sustained distorted sound as well. (I'm not exactly sure how tabbing out an Ebow section of a song even works so bare with me, however, I am indeed giving you the exact correct fret positions that Jonny actually plays so if you can't understand what I tabbed out you can still figure it out quite easily.)

 

 

G|---14~~~~--12h14p12\9~~~~--7h9p7\2~~~~--2/7h9/12\2~~~~--0---|

 

 

And here is the verse section, these are the droning notes you hear in the background when Rihanna comes in for the very first time. All played on the B string.

(Listen for the changes)

 

B|---13-----12-----8---| Repeat x2

 

And that's all I have, if anyone knows the rest of the actual guitar parts or if there's even any other parts then please let us know.

That's sweet! Accurate too! I really want an EBow but with an effect amp and pedals I've managed to get a similar sound :)