I know that my friend does live events using a Canon HV40 because it has Firewire and streams really well. I'm not sure but the streaming company that my church goes through offers us the option to video first an event, then upload the footage for streaming at a later set time like a video on demand feature.
Right now they are using an older Panasonic unit GS900? They are thinking about going with the HV40 though.
I say I don't know but maybe you could email the likes of Grassvalley and bring the video into a box via another connection and then the unit (box) might send the signal to the feed? This is all a guess since I have never tried it this way or even sent them an email asking if it would work.
Last, maybe a good HD webcam depending upon what you are going to do. If it's sports or something from a distance then this idea is out 😱