Expiring Item Instances with a Status based on previous Status

Hi-

I want most all my expired Instances to have an instance status of 'Expired' when the Expired Date is reached.  However, I'd like to set an Item Instance to 'To Be Decommissioned' (User Defined Status), and give a future Expired Date.  When this Expired Date is reached, by running the Expire End Dated Instances Concurrent Program, the Status for this Instance would be set to 'Decommissioned' (another User Defined Status) instead of using the Profile Option CSI: Instance Termination Status which has a value of 'Expired'

Any thoughts on best way to accomplish this?

Thanks-