We received these instructions from a user in a support ticket:
1. Copy the 'http:' iCal link from Band Helper.
2. Create a new Google Calendar - share it with public
3. Paste the iCal URL in to the box on the bottom of the creation form. Make sure to set your timezone.
4. From the Google Sites 'Insert' menu, select Calendar and share your newly created calendar.
I have not tested these instructions myself, but they seem relatively straightforward. If these instructions work for you, please be sure to note that here for the edification of everyone else!