From a `real' console which understands EMCA-48 CSI sequences (like Linux for example), you can use the following snippet to control the leds on your keyboard:

#!/usr/bin/perl -w
while ( 1 )
{
  print "\e[".$_."q" and sleep 1 for ( 0..3 );
}
[download]

This will turn on each individual led on turn.
For more information on see the man-page of console_codes(4).

HTH,

JaWi

-- JaWi

"A chicken is an egg's way of producing more eggs."