If you want to use this splash screen:

Open 'Program Files\Flight Simulator 9\Uires' folder.
Find dlgsplash.bmp and rename it dlgsplashbmpBAK

Paste the new dlgsplash.bmp into 'Program Files\Flight Simulator 9\Uires' folder.

If you want to reactivate the original splash, simply delete current dlgsplash.bmp and rename dlgsplashbmpBAK back to dlgsplash.bmp

That's it!