As I posted in the "technical area" thread on this topic:
You can't use a 3-wire bicolor LED (or a 2-wire) in this application.
The I-O wires the LED such that the I/O line driving the LED is active high,
it's sourcing the current to drive the LED. The cathode of the LED is connected
to GND and the anode of the LED is connected through a resistor to an I/O pin
on the chipset.
The IDE LED modification wires the LED in the opposite way because the drive
activity output is active low. The cathode of the LED is connected to pin 39
of the IDE header and the anode is pulled up to +5V through a resistor.
You can't accomplish both tasks with one common cathode LED (nor can you do
it with a common anode LED). I suppose you might be able to reverse the logic
of the stock LEDs, but I don't know how much current the outputs can sink vs
source, etc. I also didn't like the idea of changing their stock behavior
to have them remain compatible with any soft hacks some folks might do.
Have a look at my section on Fred M's web site to see pictures of how I did it.