I don't think you can. But, you could always try Miro =D http://subscribe.getmiro.com/
Of course, your guests will have to download it. But, it is a good alternative.
You can try P2P streaming broadcasting by sopcast. This servis is free and can support more users to watching you media streaming. Use this link to join with sopcast.. http://www.sopcast.com ..and the details can you read from this website.