I recall struggling with this at Apache Forrest in the past. However, sorry cannot remember how.
Search the mail archives should help. At Forrest, we now have a default configuration file at WEB-INF/ehcache.xml Maybe that will help you to control it. However, IIRC then we had fixed our ehcache debug log messages before adding that. Also, you would probably get a better response from the Cocoon users mail list. -David