I would disregard the 'cross-hairs' if your stem has a solid (no holes) front clamp, although you will need them to centre the bars in your stem (once the angle has been ascertained).
A good place to start is to put a finger into each end of the bars lightly, and let the bars dangle. The weight distribution is such that it'll give you a decent angle of reference, and you can adjust from there as necessary.
A similar thing can be done with the Onza Carbon Risers, too.
Cheers,
Adam