Outlook item to webDAV location

I have a web application which has a calendar, and I want to allow that calendar to be sync'd with an Exchange server.

I've written code to create appointments on an Exchange server directly in a user's calendar using webDAV. I save the appointment locations (URLs) so I can update the appointments in outlook if something changes in my application.

I'm trying to write an add-in for Outlook that lets a user send their appointment to my web application. In order to save it though (and allow updates in my application to propagate back to Exchange) I need to figure out what the appointment location (URL) is in WebDAV.

Is there any way to get the WebDAV URL of the appointment from within Outlook? I'm using VSTO for my outlook add-in.

Thanks for the help guys!

This question helped considerably: How to use WebDav to match dav:href to Outolook Interop href value

And this website was interesting too: http://www.infinitec.de/post/2007/03/Constructing-OWA-2007-item-ids-from-WebDAV-items.aspx