[BAMsE]

Not mine. Just founded on net. Works fine

[Files]
 Source: "Splash.png"; DestDir: {tmp}; Flags: dontcopy
 Source: "isgsg.dll"; DestDir: {tmp}; Flags: dontcopy

 [*Code]
 // p2:String -- Inno Setup (Kein UNICODE)
 // p2:AnsiString -- Inno Setup (UNICODE)

 procedure ShowSplashScreen(p1:HWND;p2:AnsiString;p3,p4,p5,p6,p7:integer;p8:boolean;p9:Cardinal;p10 :integer); external 'ShowSplashScreen@files:isgsg.dll stdcall delayload';
 procedure Splash();
 begin
 ExtractTemporaryFile('isgsg.dll');
 ExtractTemporaryFile('Splash.png');
 ShowSplashScreen(WizardForm.Handle,ExpandConstant( '{tmp}')+'\Splash.png',1000,3000,1000,0,255,False, $FFFFFF,10);
 end;

 procedure InitializeWizard();
 begin
 Splash();
 end;