[Snow]

Let's assume, your texture is named 'fuselage.png', then create a night texture and name it 'fuselage_LIT.png'.
Select your fuselage object in AC3d and chose 'Make Night Lighting' in the X-Plane menu.
When you export your fuselage, the plugin will add an additional line to your fuselage.obj:
TEXTURE_LIT fuselage_LIT.png

To use this function, the night texture must already exist.

You can also edit your object in a text editor after exporting and add that line manually.
This is what the result should look like:

TEXTURE fuselage.png
TEXTURE_LIT fuselage_LIT.png