It turns out that via a Java example I was able to figure out the proper codepath for this in Clojure:
(defn- enable-cdn [bs container]
(->
(blobstore/blobstore-context bs)
.unwrap
.getApi
(.enableCDN container)))
This will enable the CDN for a given container provided a valid blobstore instance. Maybe this will save someone else some time later.