Webcal and file_get_contents

Does anyone know if there is a simple way to convince 'file_get_contents' to treat webcal urls (e.g. webcal://www.calendarlabs.com/templates/ical/US-Holidays.ics ) as being the same as an http url? (according to Wikipedia, http is assumed for webcal urls) I've looked into using 'stream_wrapper_register', but, unless I've misunderstood it, this would require me to write the whole http access myself, without being able to just pass it onto the internal http processing code. I've done some web searching, looked through the PHP docs and had a look through the archives here, but not managed to find anything (sorry if I've missed anything obvious). Davo