I have used coffee beans several times, but never with bourbon. I would add them in the secondary or towards the end of fermentation in the primary. I will guess you will have some bourbon and coffee notes in your beer.
I'd add the bourbon to the primary. Let it ferment for a week to reduce any sugar that wants to ferment out. Add your beans and taste daily.
It sounds like a reasonable thing to try, with the caveat that I have never ventured into coffee or bourbon beers myself. But the more I think about it, the more I question making a mixture of ingredients and adding it rather than adding the ingredients separately. It's easier to adjust to taste if you do them separately.
