Step 1: Get the Stuff
1 2N3904 Transistor (experiment with what you have around, it will probably work)
1 9V battery
1 9V battery holder
20 IR LED's
As far as tools go here is what I used:
soldering Iron + solder
If you dont have the TV-B-Gone already you can get one at the Make Store: http://makezine.com/store/
Step 2: Modify the TV-B-Gone
To get rid of the lower battery holder you have to use a sharp cutting tool to break the connection on the right side of the top battery holder. Then on the left side solder a wire from the big pad through the hole that is right next to it. Now you can remove the lower battery holder and move the bigger 3v battery to the top holder.
Step 3: Add Wires
Step 4: Make the LED Array
Now bend the leads of one set to the side and attach another set between the two bent leads. Repeat this until you have filled out the entire grid.
Note: Always check the polarity of the LED's you are soldering. This configuration creates five parallel blocks of four LED's in series.
Step 5: Complete the Circuit
Now wire the positive side of the LED array to the 9V supply. Finally connect the ground and 9V wires from the PCB to the 9v Battery clip. Attach the LED array and PCB to the battery clip. You can use anything from around, duct tape will work nicely. I had some double stick foam so I used that. The End.