Assuming you have the knowledge and basic understanding of How to import 3D Models using Sketchup and MCX this is the next step/process of how to convert/edit night textures.
Program used: GIMP
Note: It's important to know that the process of creating night textures is easy, the hardest part comes down to your photo editing skills.
Step 1: In ModelConverterX load model file then proceed to edit and rename " _color " to each desired texture you would like to light up at night.
Save textures to desired folder location and export object.
Note: After exporting textures, you could be finished by simply duplicating each '_color ' texture and renaming to ' _light '
Click 'content_convert_config' and drag your 'tmb. and ttx.' files into desired folder location. And there you have it, night textures!!
But we want to make a somewhat convincing night texture!
Step 2: Right click on desired texture and or open with GIMP photo editor
Step 3: In GIMP, there are a few workflows, again it all comes down to your photo editing skills and how artistic you want to get. Remember you can find anything on the internet and any Photoshop question you have most likely can be found. www.google.com
For a bit more detailed editing I typically follow this procedure.
Select 'Layer' 'Transparency' and 'Add Alpha Channel'
Select 'Layer' and 'Duplicate Layer'
If you look at the bottom right corner you will see your texture layers. This is important and allows you to create more color variations such as windows, light bulbs, signs, etc.
Note: While editing I typically make the top layer all black. From there I use the eraser tool to mimic light paths.
: Example video of editing How to Edit Night Texture Video (a basic procedure)
Step 5: When finished editing, In GIMP click 'File' 'Export As...' and under "name" switch "color" to "light" and 'Export'
Step 6: In folder where texture files are located click
'content_convert_config' and drag your converted 'tmb. and ttx.' files into desired folder location. And there you have it, night textures!!
Hope this helps and gives a better understanding.
Big thanks to Rodeo for the help a few full moons ago!