Buy the MS Media Pro keyboard and you will have 5 programmable buttons for starting different programs at the top. The Windows and Applications keys included on all keyboard can be assigned for different programs as well.
Installing a backlight on a keyboard? It would be one thing to install a light and another to power it along with including an on/off switch. You won't be able to power it through the PS2 port. That is for input only. A usb port wouldn't provide the power level needed for a light unless it was already designed to run off of one. Battery operated reading lights for books have a clip that will extend and actually slide under the back of a keyboard. Those have a small switch for on and off on those and are low cost in department stores as well as many bookstores. The small lamp reaches up a few inches above a keyboard for shining barely enough light there to see which keys are which ones.