you can find dxtbmp here
It is a program that you use to convert bmp files that come out of your editing program (photoshop, gimp etc) to the extended bmp's (for FS9) or .dds (for FSX) files that your sim needs.
If you look in any of my texture folders, you'll see two files, p47d_t.dds & p47d_t_spec.dds.
If you open one of those in DXTbmp, you get something like this:
(this is a spec file)
You see the main image (or part of it here), but notice the little square in the top right corner? That is the alphachannel for this image.
The alpha channel controls the reflectivity on the main texture, and the intensity of the reflections in the spec texture.
The buttons below the main and alpha image allow you to save them as normal bitmaps, and then you can edit them, and import them back again.
Alternatively, you can use the files form the paintkit that you edited.
You open the main image in DXTbmp, you import the alphachannel, and you then save them combined as a DXT5 dds file, which you then use in FSX.
So, if you want to use my setting of a particular texture, where you like the final result, you open the dds files in DXTbmp, you export the main image and the alpha separately as normal bmp's and import then into photoshop/gimp whatever you're using, and copy the colors/grey's I used for your own textures. You then save those (so you'll have four files (normal, normal alpha, spec and spec alpha)), and you combine those into two dds files by importing them into DXTbmp.
Confused? So am I by now...
Give it a try and see how far you get.
You can also mail me direct, my e-mail adress can be found with all my textures.