[Evolution] iCalendar connection?

[Tom Ball <Tom Ball Sun COM>]

My calendar is accessed via HTML using Sun's iPlanet Calendar Server. 
Does anyone know of a way to synchronize Evolution's calendar with it? 
Exporting to an iCS file and importing it doesn't work; the importer
appears to accept the file but nothing gets added to my calendar. 
Accepting an email invitation does work, however, so I think that the
iCS formating being sent is OK.

I'm comfortable coding a new Evolution connector if necessary, and would
appreciate pointers to any documentation on how to create one.  Of
course, it would be much easier if that task has been already done!

Tom