The "problem" you may run into is not so much whether FSRepaint can or can't (I don't think you can because it doesn't "read" the interior model) but rather adjusting your photo to the existing assigned interior textures.

On an existing model, while you can identify the textures, you still have to work with the names and texture mappings - i.e. if you have a larger photo of the desired area, you have to crop it to fit the existing texture (or assigned part thereof)