You can't do that with EVPM.
Look in the Registry_Values.pdf/chm for the following:
ConvertExcelToText
ConvertRTFCoverToText
ConvertWordToText
Registry_values.pdf can be found here:
ftp://exftpp.symantec.com/pub/support/products/Exchange_Mailbox_Archiving_Unit/317274.pdf
Regards,