So the human says to the killbot, "My what nice infrared optical tracking and targeting system you have".
The killbot replies, "All the better to hunt with..."
First I open up the webcam (Creative Model #VF0220) and see what it looks like inside.
After the camera is opened I unscrew the lens and pry off the cap on the backside which reveals a small square infrared notch filter. Gently heating the lens module with a heat gun may make it easier to pry off the back cover. The CCD imaging module for webcams are naturally sensitivity to infrared and this filter blocks infrared to improve image quality. However since I want infrared night vision I remove this and reassemble.
Since I could not find any infrared LEDs, I tried using a heat gun as an infrared illuminator, which worked surprisingly well.
If you have more money you can try something like this or this...