First, you would have to locate the TGA file of the kneeboard. It should be somewhere in one of the CDDS container in the Bazar\World directory.
In previous times, there was a CDDS explorer available (I think, it was a feature within the LOMAN tool) which allowed for exploring the graphics container.
Once the TGA is located, you should be able to extract it from the CDDS container and manipulate it with photoshop. Be carefull to maintain the mask of the file (TGA format!).
Save the new TGA back to the CDDS container and test it in the simulation.
After some try and error cycles, you should have your version of the kneeboard available in the game.