[Chimera-users] axis - length

Hi, I am trying to display an axis in chimera. I have one point - x,y,z co-ordinates and centroid's x,y,z co-ordinates. I want to extend the length of the axis generated using this two points. I tried to create a bild format file. *.cylinder 0.584 0.048 0.810 20.912 5.823 19.703 1* where, second 3 co-ordinates are centroid. It creates an axis but i want to extend the length from centroid point to the other end too. Or, Is there any other way to define it? Please help me. Thanks, Catherine