Well, there really isn't any use for that. If you are wanting to create a GCT, go to geckocodes.org. And if you are still wanting to change it, just change the file extension to *.txt. :)
Quote xcoopa how do you change a GCT code in to text format?
I don't think there is a program for this. But there should be a program for the reverse. If you look at that programs source you could find information about how you'd do to reverse it.