Well, there's the proper way that Pags alluded to, namely collect the juices from the rib, degrease them after cooking, add water and/or wine, then boil down to concentrate flavors.
Sounds good, but I've never tried it in a smoker and don't think it would work.
If you can find Lawrey's Au Jus mix go with it. It's great!
I usually make au jus with Minors beef base with celery, carrot, and onion added for flavor. Then thickened very slightly with corn starch. you can add wine or spices as you see fit. It might not be proper French au jus, but it's better than most restaurants serve.