You are doing this with NetStream? Then you can create a
movieclip and use attachSound to attach the sound portion of the
NetStream to that clip. Then you can use the usual Sound class
methods to control the sound.
There is a tutorial at gotoAndLearn.com, but I can't remember
exactly which part this is in.
Or search the forums for attachSound. If you can't find
anything post back and I'll see what I can dig up.