You canspecify a "tika.config" option pointing at your own tika-config.xml files that ExtractionRequestHandler will use to configure Tika with...
http://wiki.apache.org/solr/ExtractingRequestHandler "The tika.config entry points to a file containing a Tika configuration. You would only need this if you have customized your own Tika configuration. The Tika config contains info about parsers, mime types, etc." -Hoss
