Hi Paul, I've actually recently posted about this as I was thinking about it, but I had suspicions over the curtain airbags and rightly so - I was advised by the guys on here that they'd need to be disabled and thus why not many people do it.
I've seen one or two with velour retrim, but I'm spraying mine black instead; look up 'simply upholstery spray' on google. Cheap and looks like it'll do the job