Hi Aaron,
I am still not quite sure of what you want to do. But it seems to me that once you've figured out where your vectors intersect the sphere, all you need to do is display these intersection points in SUMA.
So, I still think your best bet is to see how one displays various types of objects in SUMA using the demo @DO.example . In there you will find ways to display vectors, points (as spheres), planes, text, images, etc. anywhere you like in the rendered scene, or on the surface.
Regarding ConvertSurface, it is a command line utility that comes with afni's binaries.
cheers
ziad