I have been giving it some thought, but am still a little confused...

ang_for_axis(ANGLE* vAng, VECTOR* vAxis, var angle);

The way I understand this function (which is probably wrong) I think the values I would need are as follows?:

vAng=vector(desired_pan,0,0);
vAxsis=N
angle=a

Being "N" a normal vector perpendicular to my vehicle position relative to the planet center?
And "a" being the tilt if my vehicle faced the planet center +90?