I use FreeTrack, and while it doesn't exactly require LEDs it works a lot better with them. Just like TrackIR it doesn't work well in all lighting conditions without something with LEDs. The Freetrack forum has plenty of information on making your own LED thingies, so I'd suggest you look around there a bit. If any questions remain after that I can help you, since I've already made my own cap with IR-LEDs. It's a direct copy of the "commercial" cap design I linked below. I assure you, it actually works
One alternative is to buy a ready-made LED cap from
here
or you can also use
this with Freetrack. It's practically the same as the self-made things.