A script to do the heavy lifting of converting export sheets from the old system to FreeMarker would be useful.
Note: The script will cover only the majority of cases. If it does not understand a line it should leave it unchanged and report it.
Groovy script created. See code/convfreemarker.groovy
Usage: groovy convfreemarker.groovy sheetname [outputtemplatename]
You can get groovy from http://groovy.codehaus.org/