This is possible to do with a script.
I think you'd have to find the objectID of the sun, and the skybox and change the resource.dml, flareBitmap, and position.
Nah you gotta recreate them really fast.
And you don't gotta get their objectID.
They are always called Sun and Sky.
So you can do simple commands like Sky.delete(); new Sky(Sky){ etc...
I could be wrong on the class name there, but that's how it works.