Youve gotta remember that slash doesnt play that fast run anything like as good as it is on the record when he plays it live. Its highly simplified and improvised.
The best thing to do it write down the notes he uses, and then use then in any order. Its not essential to get it exact, nor would anyone notice.
When i play than fast run I just use random hammer ons n pull offs with the 7th,8th,10th,12th,14th and 15th frets. And a couple of notes from the 2nd string too of course!