Certainly!!

What you need is a program called DXTBmp. You can download it from Martin Wright's website @ http://www.mnwright.btinternet.co.uk

Once you have this program you can convert aircraft textures to standard 24-bit. If applicable, export the Alpha channell. Once converted, you can edit it to your hearts content in you favorite image editor like Paint Shop Pro or Photoshop.

Once you're done, open it up with DXTBmp, import the Alpha channell that you exported, and save as DXT 3 W/ Alpha. Now place the texture file into your aircraft folder and test it out!

I may not be completely right, but you got the jist of it

If you run into more problems, head over to the repainting forum, or read the tutorials located on the HomePage

Good luck!