We ran into the same question, but unfortunately Active Queues do not seem to function in that way. I believe Blue Prism's intention was to include a dynamic queue function in the future. (As we are on version 5, I may be unaware if such a feature exists in version 6.)
That being said, it is possible to control Blue Prism via the command line and the http interface, and work queue information can be queried via SQL. We were able to create a custom solution that launches processes on the robots based on the work queue status. It is possible to achieve what you're looking for, just not with the built-in control room features.
