Turn on aircraft reflections: Settings>Display>Aircraft for starters.
To learn to do a repaint with reflective textures go to:
www.gjsmith.net, then as follows:
Tutorials>Complete tutorial>Painting aircraft textures>Step 6.
A direct link to Step 6 didn't work, so you'll have to follow the path I've outlined & scroll down each page to find the exact next link.
Essentially you're applying an alpha channel to the texture. Not all textures can be repainted like that, they have to be DXT3 to begin with. The process may differ from the tutorial somewhat, but you should be able to adapt it with a little experimentation.
The invisible Corsair was not a DXT3 to start with, probably a DXT1, so applying the alpha channel per the above renders the texture transparent.
Whereas I know how to do this, I can't really get more technical than this as for me it's a mechanical step-by-step process. Additions and corrections to this are welcome.
Look through the Aircraft Repainting forum for more info. The mods may move this thread there, by the way.