How to use Rules to change Workflow status in ProsePoint

I'm working on the redesign for a daily newspaper's website. I'd like to find a way for the Workflow status on stories to change automatically after a week from "Public" to "Archived." I think this can be done with the Rules module ... but I haven't figured out how yet.

I've read some information about using Workflow and Rules together in various places on Drupal.org, but most of what I've read is based on the workflow status being a CCK field. This is not the case in ProsePoint, where Workflow is built in, but not in a way that presents a CCK field that Rules can work with.

I'd appreciate any help I can get; if you need more details, let me know.