Make sure you have DavMail running.
In iCal, go to Preferences in the menu. Click tab Accounts. Click + to add a new account. Choose CalDav from drop down list as account type.
Enter username and password. For the username, add username only, and not domain\username.
As server, add something impossible like ‘loca’.
The software will complain after you click Create. Ignore this warning, and click Create again. This will open a more complete entry form. This time, enter
- Server: ‘localhost’
- Server path: ‘/principals/users/<your email address>/’
- Port: 1080
- SSL: leave unchecked
You should now see your Exchange 2003 account appear in iCal.
Guy Coen's Weblog 
There are some issues currently that result in complaints about a missing “home” calendar. Discussions are still ongoing about possible resolutions and bug fixes. Here is what helped in my case to resolve the problem:
1. Revert back to DavMail version 3.9.2
2. Remove file .davmail.properties in user home directory
3. Re-start DavMail
4. Re-create CalDav account, but remove the trailing / in the server path
Setup in iCal after setting up DavMail for Outlook 2011. Works perfectly! thanks again for posting!
I had some issues about missing ‘home’ calendar…I didn’t bother with steps 1-3 above, just step 4 and it worked for me.
However, is it possible to view a colleague’s shared calendar using DavMail? I have tried subscribing to their calendar using the url ‘http://localhost:1080/principals/users/user@company.com’ (as per the DavMail FAQs but I keep getting the following error….
“There was an error subscribing to the calendar.
There was an unexpected error with the request on subscribed calendars (error -1)”
I hope you (or anyone) can help…really at a loss!