Aircraft reflections

I've been reading some tutorials on how you can specify the reflection amounts by altering the grey scales in the alpha channel of your BMP textures.
So does this mean that if I edit the main BMP file for say, the default Cessna 172, and make the alpha channel a lot darker, it will make the plane's exterior a lot more shiny? Or even completely chrome? Or do I have to actually do something more in Gmax to make this work?
I was unsure whether to post this in this forum or the Repainting one, but I guess it's relevant in both.
Many thanks.
Chinookie.
So does this mean that if I edit the main BMP file for say, the default Cessna 172, and make the alpha channel a lot darker, it will make the plane's exterior a lot more shiny? Or even completely chrome? Or do I have to actually do something more in Gmax to make this work?
I was unsure whether to post this in this forum or the Repainting one, but I guess it's relevant in both.

Many thanks.
Chinookie.