If you just want them ON when the cab is on, all you need is a 5v supply line, and a resistor (usually about an 80-100ohm) for each LED.
The LED's you can get from radio shack, or hack them out of whatever devices you might have that have them.
You usually wire the resister to the negative side of the LED, then wire that to ground. Wire the positive side of the LED to 5v (you can get that from the PC's power supply, or a USB cable (just search for USB PINOUT for which wire is which in a USB cable)
If you're only driving 2 led's, that shouldn't be an issue.
If you want the LED controlled by an LED wiz (which it looks like you have one from the picture), you'll need to run a wires from the wiz up to those leds, but otherwise the wiring I've described is the same.
and If that IS an LED wiz in the photo I'm seeing, looks like you've got plenty of open ports to wire 2 extra LED's into.