Well! A kind soul pointed me to: (URL) has a neat Winamp plugin that allows the program to be controlled by the serial port. Now I just need to convince the IR tower to play nice with others. The plugin tries to open Com 2 (where my tower's plugged (...) (25 years ago, 17-Feb-00, to lugnet.robotics.rcx)
(...) Mindstorms uses an ActiveX control called SPIRIT.OCX to communicate with the IR tower. As far as I know, it only opens the COM port when some application is actually using the .OCX, so the port should be available for use if you're not running (...) (25 years ago, 17-Feb-00, to lugnet.robotics.rcx)