Get spherical coordinates of a hotspot that is not in view.

Hi all,
i try to explain me in the best way that i can.
What we need is that the spheretoscreen function (or a similar one) also accepts hlookat and vlookat as parameters so that we can calculate the coordinates of a hotspot even if you are not in the view.
Or if there is a some alternative way to do that.
Thanks a lot!!