Read this article below how to generate iCal URL from Microsoft Exchange:
How to export to iCAL from Office 2007
Before you proceed with step below, validate your iCal URL using site below:
Go to Claromentis Calendar and click “Import” as indicated below enter the iCal URL, select target calendar to import, You might want to create new group calendar for this purpose.
Thanks to David from Prometheus for the continued contribution to this wiki.