Make sure you are using the latest MS Exchange pathces:
http://www.microsoft.com/exchange/downloads/55/sp4dl_en.asp
Additionally, make sure you have copied from Exchange the ExCalcon.exe file. Then in the Notes.ini add the following to your servertasks= line
excalcon 'PlaceExchangeServerNameHere' exchange.box
I have this working with R6 and Exchange 5.5.