The Content Management System add-on for BlackBoard uses WebDav as its format for shared folders. This means that CMS Folders can be used for hosting WebDav friendly files - e.g. iCal!
Then all you need is the url to the WebDav content, to be able to share it over the Internet.
My wiork iCal url is: webcal://kowhai.unitecnology.ac.nz/bbcswebdav/users/tcochrane/iCal/TC_LTcalendar.ics
(note - you need a BB CMS login and password to access it!)