I built a Mac version with a very hackish Makefile:
http://www.shatters.net/~claurel/celest ... im-mac.zip
It's command line only. Unpack the zip, then go into the directory scattersim.app/scattersim and run it:
scattersim -l earth.cfg
...and you should get a nice image in out.png. The -l option tells scattersim to use lookup tables to accelerate calculations. Any differences from the image generated without lookup tables should be very minor. You can omit the -l options if you're seeing something peculiar in the output that might be caused by the optimization. Use it the rest of the time because it makes the program run much faster. Here are the rest of the options:
Usage: scattersim [options] <config file>
--lut (or -l) : accelerate calculation by using a lookup table
--width <value> (or -w) : set width of output image
--height <value> (or -h) : set height of output image
--image <filename> (or -i) : set filename of output image
(default is out.png)
--depthsteps <value> (or -d)
set the number of integration steps for depth
--scattersteps <value> (or -s)
set the number of integration steps for scattering
I'll explain the contents of the cfg files later; if you're familiar with the new Celestia 1.5.0 atmospheres, you'll recognize that the parameters are very similar.
--Chris