Alpha channel/aluminum on gimp?

Hi.
I'm currently using GIMP 2.6 to do my repainting for FSX. What I'd like to know is, is it possible to make a reflective/shiny surface for FSX aircraft with GIMP? You know, like the aluminum on planes operated by American Airlines? If anyone knows how to do this, please post how...
I'm currently using GIMP 2.6 to do my repainting for FSX. What I'd like to know is, is it possible to make a reflective/shiny surface for FSX aircraft with GIMP? You know, like the aluminum on planes operated by American Airlines? If anyone knows how to do this, please post how...