yes it's possible.
adobe media encoder is one of the possibilities.
VLC will do the job too
M$ has also it's own software
you need a TV-Card and according to the number of your audience one or more relay-server.
So you stream your TV-source to one server and the users will connect to this server.
if you just do a normal relay-server then they musn't be that strong.
if you want to do encoding, encode it on your own PC - so you can buy cheaper servers.
On VLC klick File -> stream -> choose your source, klick stream -> choose your destination (http probably) klick on add
klick on start -> et voila a stream has startet.
with adobe media encoder you need to have a server configured that use... öhm i've vorgotten - sorry.
you can choose which destination you want to stream to (e.g. wowza)
but i don't know how accetly this will go.
if you use a service like wowza they have a lot tutorials showing how to stream
