Hi,
I'm not sure I understood the question right, but I do broadcast UDP packets to 192.168.1.255 with [netsend] in my every day life in UDP mode, i.e. [netsend 1]. Just send it a [connect 192.168.1.255 3000( message and use a [netreceive 3000 1] (1 means UDP) in the receiving machines. Port 3000 is just an example of course.
However, if you mean TCP broadcast... I feel so ashamed but I don't even know if that exists.
No idea about multicast either.