See Also: Mass-editing of MP3 Tags
See Also: Rename Scripting forum.
This is easy to do with Opus and is described in the PDF manual under Predefined Commands - File Commands - Rename. At the time this FAQ was written the information is on page 141 (page 150 in Adobe Reader since it also counts the unnumbered pages at the start of the manual).
Below is an excerpt but there's much more information in the full manual: