|IGN.com did an interview with Marco Beltrami and they asked him about working with GN'R. Here's the GN'R part of the interview:
IGN: Since we're talking about rock musicians, what was the deal with you arranging some orchestral sections for the impending Guns N Roses album?
Marco Beltrami: That was sort of just work for hire. I guess they'd heard some of my orchestral music of mine. I met with Axl and he played me these songs, asked me my ideas about them, and I told him what I thought they needed. They gave me four songs to orchestrate. A couple of them I did more than orchestrating, I actually wrote some melodies and stuff. It was a fun project. I really enjoyed it. The music was eclectic and at the time that I was doing it there were no lyrics on the songs that I was working on. People ask me about the album and I really have no idea about the release. I thought it was coming out last September. I'm the wrong person to ask about that.
IGN: He came to you with the tracks then, so you weren't ever in the studio with the musicians or anything like that
Marco Beltrami: No, they had finished tracks. On one song I actually wrote a guitar part, but they pretty much had the band tracks down and then I added orchestral stuff on top of it.
IGN: What songs were they, by chance?
Marco Beltrami: A song called "Seven," which is the one that I did the most work on, I actually did some writing on. There was one called "Thyme," one called "The General," one called "Leave Me Alone."
IGN: How was that as an experience? Do you have any future plans to work with more rock musicians or is it more like you'll take it as it comes?
Marco Beltrami: I enjoyed it quite a bit. It was different than doing film music, but it was a lot of fun. I would probably do it again. It would probably be more fun at some point, to do it as a more collaborative affair, starting more from scratch, working and writing stuff [together]. But it was definitely fun.
You can read the rest of the interview here.