Hi,
To implement live streaming in ASP.NET, I think generally you can develop a client side application (Silverlight or Windows Application) to record audio and video, and then send the data to the server by using Web Services.
Anyway, maybe these threads can give you a help.
Live audio-video streaming in an asp.net website
http://forums.asp.net/t/1607008.aspx
Flash live video streaming in asp.net 3.5
http://forums.asp.net/p/1322826/3231932.aspx
Hope this helps.