That being said the packages (without online installer) are also available for direct download when you know where to look... [see link below]
If you're on Linux though the situation is much simpler since your distribution most likely already packages the Qt libs so you just use your package manager to install them and off you go...
Regardless, for anyone looking for a native portable toolkit, I don't really think there's anything that comes close to Qt in terms of functionality and tooling (like Qt Creator and Qt Designer) and once you get over the idiosyncrasies and quirks its really quite good (for the most part).
