The patch is installed through the SugarCRM Module Loader and you must 'Clear Vardefs Data Cache' for the ProjectTask module from the Repair section of admin as the patch adds a few fields that the SugarCRM team removed. Once the patch is installed you may want to use the Studio to replace the Date Due fields for ProjectTasks.

Each user should specify a Publish Key in the Calendar Options of their MyAccount section in Sugar. Note: this key will be transmitted in clear text and shown on the screen in iCal and SugarCRM's interface so don't use your regular password.

Once the key has been specified go to iCal and choose Subscribe from the Calendar menu item. Enter a URL similar to:

replacing YOURSERVER, YOUREMAIL, and YOURKEY with their appropriate values.

You can also use user_name and your username in place of the email field. (This is virtually the same as the URL given in the My Account section of SugarCRM with the exception of type being ics instead of vfb)

Alternatively, you can just specify:

and let iCal prompt you for your username and key (not your actual Sugar password).

The default encoding will be UTF-8 but you can override that by specifying the encoding in the URL: