Is it possible to stream mp3s with XMMS, via IceCast, like in WinAmp+ShoutCast DSP?
Yes, it is possible, but not very easy. You might be better off with using some other streaming source than XMMS, for example MuSE (mirror site). On the other hand, if you really insist on using XMMS, the only working solution we know about is using OddCastV3 with JACK and ALSA, and XMMS with XMMS-JACK output plugin. The setup is not trivial, but there are some tips on the OddCastV3 documentation. There is also a very old, unmaintained and most probably broken XMMS plugin called XMMS-LiveIce. Several users have reported that the plugin does not work. Since it is 3rd party, don’t bother XMMS developers about it – we don’t care.