Before you show any messages, you need to set up the number of steps you will show. For example, the KDE startup procedure uses 7 steps.

    QByteArray data;
    QDataStream arg(data,IO_WriteOnly);
    arg << someNumber;
    if (!(c->send(KSplashName, "KSplashIface", "setStartupItemCount(int)",
data))
      // Some error processing here.

Whenever you want to display a message with or without an icon, use

    arg << QString("iconName") << QString("programName") <<
QString("Some description");
    if (!(c->send(KSplashName, "KSplashIface",
"programStarted(QString,QString,QString)", data))
    {
      // Some error processing here.
    }

Each time you call programStarted, the steps completed is incremented. When your program has finished its startup, do the following to make the splash screen go away:

    if (!(c->send(KSplashName, "KSplashIface", "startupComplete()", data))
    {
      // Some error processing here.
    }

That's it! You don't need anything more to take advantage of all that KSplash has to offer you.