Enter the directory where you extracted the source code and run:

$ mkdir build
$ cd build
$ cmake .. -DCMAKE_INSTALL_PREFIX=`kde4-config --prefix`
$ make
$ sudo make install

You may then find the GRUB2 KCModule under "Startup and Shutdown" in System Settings.
You may also launch it running:

$ kcmshell4 kcm_grub2

In order to appear in System Settings the first time you install the GRUB2 KCModule, you may have to run:

$ kbuildsycoca4

Requires KDE >= 4.4, Qt >= 4.6, GRUB2.
Suggests ImageMagick for GRUB splash image management.
Suggests hwinfo for valid GRUB resolution detection.
Suggests LibQApt or QPackageKit for removing old entries.
Minimum requirement is kdebase-runtime. Install kdebase-workspace for System Settings integration.

Note: '$' indicates a shell prompt.
