I've done several standard stouts and added beam aged oak chips to the keg. Best result were lightly toasted chips, soaked in beam for six months or longer. Added about 1/3 cup to the keg in a hop bag. Taste was best between 3-6 months. Longer and it seemed to get bitter. Same with adding the liquor.
I'm going to go look for that beer. I'd pay 20 to try it.
I'm drinking a local brewpubs 2008 imperial stout aged in beam barrels for 3 1/2 years right now.