It's a program that's actually used to map things like MIDI controllers, Wii-motes and PS3 controllers to actual keyboard commands, but naturally also works with regular keyboard remapping!
Start up PIE. Choose the "File" Menu,
then click "New". This will clear
whatever was in the big white box so
you can type your own script. We want
the W key to be controlled by the up
key so type this on one line then
press Enter:
W = Up
This is a working PIE Script so you
can test it by choosing the "Run!"
menu and clicking "Run".
Whenever you press the up arrow key
(on the cursor pad, not the numeric
keypad) it will type a "w". Try it
out! This will work in any program.
Note that it will still move the
cursor up. The Up arrow key still has
its original function, but it emulates
a w at the same time. Try holding down
shift and pressing Up. It will type a
capital W, unless capslock is on.
Unlike the real "W" key, holding down
the Up arrow will only type a single
"w".
Now chose the "Run!" menu and click
"Stop". This will return our keyboard
to normal.
Now do the other keys like this:
A = Left S = Down D = Right
(Don't worry if the S is orange, that
is because S is also an abbreviation
for seconds).
Save your script as Tutorial1.PIE by
chosing the "File" menu then "Save
As...". And run it again. Stop it when
you have finished playing.
Best Answer
Short answer:
It's all keys or no keys. With levels of brightness.
Longer (warranty voiding) answer:
There is no way to customize the brightness of keys individually... Unless you want to mod your keyboard.
As advertised, each key is lit individually meaning there is at least one LED per key. However, every single one of these LEDs is connected to the same controller, which makes them all do the same thing at the same time.
In order to have individually customizable key brightness you will need to take your keyboard apart, solder things, rewire the LEDs, possibly setup your own controller for each individual key, make sure everything fits, and eventually put everything back together... cocasdaneve has great instructions for modding the BlackWidow and chart/explanation of how the LEDs are wired.
This mod does not make each key unique, it is, however, a great place to get started.
There are very few keyboards I can think of off the top of my head that have keys that are individually customizable; However, if you are after complete customization and have very deep pockets, check out the Optimus line of keyboards.