I have lost 2 nights worth sleep over this and it is extremely frustrating, when making a mod, how in the hell do you replace or make your own loading screen?
It is NOT splash.bmp, there is nothing even resembling the loading screen in any of the wads, or the pak file, and it isn't in GFX, the only thing i have found is a wad called 'cached.wad' with 2 images in it, BACKCON and LOADING, tfc and dmc have this but in every cached.wad there are no images, and the names are greyed out and you can't select them.
I have tried making my own wad, using the exact same naming conventions and saved it as cached.wad in my own mod folder but it only made the game freeze on loading a level.
Figured it out, http://twhl.co.za/tutorial.php?id=66 lets you do precisely this, overlooked the mod setup tutorials, whoops!