Subscribing to iCal feed in Backpack

OK, here's the deal. I wanted to subscribe to my private iCal feed in my Backpack calendar. There is functionality for this and I have been able to subscribe to my Sandy feed in iCal. In order to help with the issue on their end a 37Signals rep told me I'd have to give them my private iCal feed URL. I'm not inclined to do so. Is there anything that you at Values of N can do to work with the 37signals folks on this? I'm rather tired of trying.