I've used live streaming from Mixmeister, so you can definitely do it from Madtracker too.
You'll need the usual tools for Winamp (Shoutcast DNAS + Shoutcast Source DSP). Then in your Windows sound control panel select "What U Hear" (or "Stereo Mix" or whatever have you, depending on your soundcard) as recording source, open linein:// in Winamp and start streaming.