I asked:

>> Can anyone point me in the right direction to make XFree86 beep to the
>> external speakers instead of (or in addition to) to system speaker?

Christian Biere <christianbiere@gmx.de> suggested:

> One solution is to connect the PC speaker output of the mainboard to the
> soundcard instead of the internal beeper. Most soundcards have two pins
> for PC speaker input. You can then use
> 	mixerctl -w inputs.speaker=<value
> to adjust the volume or at least, turn the sound on/off.

The physical connection must be what is missing; the mixerctl values
seem to already be correct:

   # mixerctl -a | grep speaker
   inputs.speaker=255
   inputs.speaker.mute=off

When I'm back at work on Monday, I'll open the case and see if I can't
find the right connection to make.  Thanks for the pointer.

Anne.
-- 
Ms. Anne Bennett, as a private citizen:  anne@porcupine.montreal.qc.ca
Also reachable more officially at work:  anne@encs.concordia.ca