I think just what's on the page, but there's a bit of info there. It sounds like they take the green beans, then put them in the charred bourbon barrel (there's a photo in the slideshow), then "age" them (it doesn't say for how long), then after it's aged they roast them.
I am also very intrigued and keen to try it. It's odd that I can't actually find it on their website, only from the direct link.