Any way to trigger a Mass Update (Reassign Territories) using workflow actions?

We've got an issue where Sales Territory Routing (SFA) is not working on some of our inbound Prospect records because one of two key fields can't be populated on the initial Web Services Add record call. The second field is set on an Update.

The ultimate solution is to have our developers fix their process so that the record gets created in a single Web Service job. That's not likely to happen any time soon.

Instead I need a workaround to get the Sales Rep assigned on these records once the fields are finally added.

My first and easiest solution was to use the Reassign Territories (scheduled Mass Update) using narrow search criteria unique to this situation. The problem with this is that the minimum frequency for a scheduled Mass Update is once per day. That won't work because we have a minimum four hour response time for our Sales Reps.