CPack + Qt IFW, QIFWDIR environment/CMake variable

Pl45m4

I'm messing around with the Qt Installer Framework and CPack, for a private project and for the sake of understanding.

I watched the Qt Summit Video presented by Christopher Probst as well as the written guide on ICS

The part on how to intergrate Qt IFW into CPack says that it is necessary to set a bunch of variables in CMake like

set(CPACK_GENERATOR "IFW")

OR (as used in the guide):

set(CPACK_IFW_ROOT "C:/Qt/Tools/QtInstallerFramework/4.1/") #QTIFWDIR is used by default

Of course the hard coded path is not the cleanest way, but as mentioned in the comment QTIFWDIR is used as CPACK_IFW_ROOT.
However, none of these variable are set/present in my default configuration... not in CMake and not in my system's environment variables after installing the Qt Installer Framework (ver. 4.8).

I looked it up in the CMake manual

which also mentions these variables (QTIFWDIR can be both, a CMake and environment variable).

But how to set all this? Manually? This can't be the solution :D
Did I miss something when installing the Installer Framework?

At some point you have to provide a path to the location of Qt IFW, right? I don't see any CMake or environment variable in my config which points to the correct directory.

Any help appreciated :)