Night Textures for RKTN

Hello everybody,
Looking at RKTN (Daegu International Airport) scenery
The author's readme says that this is freeware and you are free to do with it what ever you like.

Since the scenery does not have night textures for the terminal, I thought I would see if I could add these to the scenery. No problem with creating the xxx_lm.bmps. However I don't know how to proceed with inserting these into the scenery. So tried the MS Coplot AI app to see if I could get a "how to"....and this part of their reply stumps me:

Using ModelConverterX (MCX):
Load your 3D model into MCX.
> I loaded: 2d195b4a47e1e972a2396aaa6aa36875.mdl

Then it says In the material settings, ensure that the existence of the night texture is mentioned.
>When I open MCX and import the mdl, I see several settings in the menu but no "material settings" and thus no way to proceed with the next instruction:

Apply the “Add night texture” template to the material:
This template associates the day texture with its corresponding night texture.
For example, if your day texture is rooftexture.dds, the template will assign rooftexture_LM.dds as the night texture.

OK...can someone help me with this? What am I missing or where did I go wrong? Thanks for any insight here...

Thanks for the reply Gunther. I was able to insert night textures (yes, all bmp files) for the terminal and recompiled, but for some reason, while the windows displayed correctly, the exterior walls mostly displayed their daytime textures. Only a couple of sections did displayed the lm textures. All textures appeared correctly in DXTBMP.

Guess there is more involved with this than I thought, but it was worth a try anyway.

Again, thank you for helping with MCX.

Steve