You could easily map a 2-d starfield to a sphere. I did this in Bryce a year or so ago. As I recall it was really simple. Another old Bryce trick you could use is to take a tiny cube with a fairly light texture replicate it many times and position the results so that they appeared to be distant stars (vary the color somewhat and there you go.) - but what do I know? I just got XP SP2 to install today after a year of trying.