Hi Roger
Try posting in our accomodation forum, and also contact http://www.gov.im/tourism/
This is the government tourist site, and they have access to the available places.
However, I am almost certain you will not all be able to stay in the same place, as the Isle of Man has only a limited number of hotels, which are pretty much full now, and they don't have hostels or large places to stay.
Have you considered camping?
Helen (admin)