IndexVolumeReplay did not give you a status bar either. Only events in the application log give you the status of the rebuild.
The informational Event ID to show the status of the index rebuild/update/repair process was introduced in Enterprise Vault 2007.
In Enterprise Vault 2007 the Event ID is 7305
In Enterprise Vault 8.0 the Event ID is 7314
The Event ID is generated every time the Indexing service has indexed 10,000 items.
The event includes: index volume identifier, index volume path, job id, job author, job description (update/rebuild/repair), job elapsed time, processing time, number of items added, additions abandoned, items deleted, percentage completed and an estimated remaining time.