Crosses or circular markers, like LEDs, seem to work well in Boujou (and Live
and 3de also). Markers in shots that I have worked on tend to be paper crosses stuck on walls, etc, or LED's. Bright colours that show up against the background are good, such as red, but I've also found that it can be good to track in black and white. As long as you can distinguish between the marker and background easily, and can tell what is the centre of the marker, you shouldn't have a problem.