Putting this here for posterity ;)
For as long as I’ve been using Windows 2008 R2, I have not been able to change the Message Queuing configuration settings (such as storage limits, storage locations, security, etc.) or access the System Queues (Journal messages, Dead-letter messages, Transactional dead-letter messages); all attempts at doing any of these things resulted in a cryptic “Access is denied” error. Whenever I needed to install Message Queuing on a server in our environment, I used Server Manager to install the Message Queuing Feature.
On a whim, rather than install the Message Queuing Feature, I instead choose to add the “Application Server” Role. Adding this role automatically selected and installed the Message Queuing Feature, though it only enabled the Message Queuing Server, not Directory Service Integration and Message Queuing Triggers.
I am now able to re-configure Message Queuing settings, as well as access and perform actions on the system queues.