I made one of these years ago for a Wii Whiteboard project. The project never got funded so the flashlight/pointer ended up sitting in a drawer. Recently a friend wanted to resurrect the project and wanted me to build him one of these lights. Since it's easy and cheap it seems like a good instructable subject.
Step 1: Items & Tools
Maglite Solitaire flashlight
IR LED(276-0143) from Radio Shack (or anywhere else)
Multimeter. You can wing it without. You have a 50/50 chance of getting the LED in correctly the first time.
Dremel with bit. Small grinding cone would be best but I did not have one.
Step 2: Open and Pull Bulb
Take the flashlight and remove the lens cap.
With the cap removed pull on the light a little bit until it's partially removed. At this point you can put a battery in the flashlight and test with a multimeter to find the positive/negative side. (But since there are only two ways to put the LED into the socket and putting it in backwards is not going to hurt the LED I just used trial and error.)
Pull the light completely out.
Step 3: Modify Lens Cap to Fit LED
Open up the hole in the lens cap to accommodate the LED.
I used a dremel with a regular drill bit on it. If you have a conical grinding tool it would be better but I did not have one.
When using the dremel wear safety glasses as small chunks of plastic will be flying. Also, be really cautious when opening this opening up as it's easy to let the dremel get away and gouge either the plastic reflector or the Al threading.
Keep opening up the hole until the LED will 'press fit' in.
Step 4: Insert LED
Insert LED into socket. Verify that the LED lights up. Since this is IR you will not be able to see it with your eyes. Use a camera to look at it you should see a purplish light when the LED is on.
Step 5: Cut LED to Size
Cut the leads on the LED to the approximate length of the original bulb.
Then bend the leads so the LED will insert all the way to the base of the flashlight.
Step 6: Finish
Screw lens cap back on until the led has pushed into the reflector. Once the cap is on to a certain tightness the LED will light. A little tighter and and it will turn off. i.e. it should work just like the original flashlight.
Since you cannot see if the light is on or off you will need to use your cell camera or some other camera each time to make sure you are turning it off.
Showing directly shining into camera. Two shots of reflecting off of white surface.
To use this kind of flashlight you will need to tilt the flashlight toward where the wiimote is so it will see the light. To 'click' just change the angle from pointing at the wiimote to flat against the surface. This way the light will disappear to the wimote which is how it 'clicks'