Hello, Sean

I've been away from home for the new year holidays, and could not reply to your post before.

You have to solder a few LEDs in a series connection (cathode of one to the anode of the other and so on), place a resistor in series with this string and connect everything to a battery.

So, it's fairly simple, but we have to know:
- How many LEDs would be necessary? Maybe do a test with say 3 LEDs and 4 penlite batteries?

To do that test, pick the highest efficiency LEDs you can find (it means more light) a battery holder for 4 AA batteries and one 56 ohms 1/2w resistor.
Connect everything in series a stated above (for the test you don't even need a board, do a kludge) connect through wires the cathode side to the negative of the battery and the anode side to the positive, do not forget the resistor.

By then you will have IR light to do a test.

Let me know if you have any doubts on the above .

Jorge O