you make a glow map

take the texture of you're ship and make it how you think it should look with no outside ilumination, the effect looks best if you take into acount things like reflection.
two good methods would be
1 simply raising the contrast super high, this is only good for ships that have simple colors as iluminated (most fs1 fighters)
2 if there is a specific color (like shivan red) do a color chanel split, add the two colors (for shivans this would be green and blue) you don't want together and divide by 2 then subtract the green+blue/2 from the red, then ether colorize it or multiply it by the origonal source texture
the last step simply name the texture"name of sorce texture"-glow as an 8 bit palitized pcx file
feel free to look at the glow maps I have included, might be good to practice on some of the textures I missed