Echo3 includes a tool to convert stylesheets from the Echo2 format to the Echo3 format. This tool is provided in the Echo3 distribution in a JAR file located at Util/Echo3_StyleConverter.jar.
To convert a stylesheet, invoke the following command from a shell / command prompt:
java -jar Util/Echo3_StyleSheetConverter.jar [inputfile] [outputfile]
Replace [inputfile] and [outputfile] with the location of the Echo2 stylesheet and desired output location of the Echo3 stylesheet respectively.