1. Using a basic LED flashlight (i got mine at the grocery store for 99 cents), remove the rear access/switch. Take out the battery housing. Punch out the led holder, board and lens using a solid but not sharp object. I was able to use my finger, but some may be glued in a bit better than mine.
2. Unsolder the LEDs. On my first one, I took them all off, but for this example I will only take the center one out. When you remove it, you will have to unsolder the spring contact as well.
3. Cut laser diode leads to about 10mm in length and remove insulation. Put wires through LED through-holes, paying attention to which is negative/positive (usually a resistor is attached to the negative lead). Solder in place, using a small non-conductive barrier to isolate the positive solder blob from the springy thingy. Snip unnecessary wire off.
4. Using a drill bit just a small bit bigger than laser diode, drill out the center hole in the reflector to enlarge it so the diode fits. Also drill a hole through the lens at the exact center, not to one side like i did... (heh). Fit the diode and LEDS through the reflector and the diode through the lens and reassemble! Done.