Additionally, all of the functions may take as their first argument an optional map of credentials:

(def cred {:access-key "aws-access-key"
           :secret-key "aws-secret-key"
           :endpoint   "us-west-1"})

Buckets are global. What do you mean by “get a bucket in another region”?

Sorry, bucket names are global. Buckets are in a particular region, of course.