this depends on how you want to stream it. Apple distributes a free product called quicktime streaming server (avalable from their website) which needs to be installed on your server to stream.
if you don't have access to the server an easier way might be to save the file with internet headers.(i'm not sure if mp4 supports this, check the options under the quicktime PRO export menu) this will give the effect of streaming, the file will start playing before it is all the way done downloading.
--will