I just came across this on the internet and though it was pretty cool:
Steps to building an Infrared Filter for your digital camera
It teaches you how to build a homemade infrared filter for digital cameras with things you can find around your house, although 35mm film is becoming less frequent.
As soon as I can obtain some processed film ends, i’m going to try and make one for my camera. I’ve already been able to confirm that a Canon 10d is capable of seeing infrared through a test I did so I assume the 20d and 30ds can as well.