Here is razorqt-0.4.1 build for kde-4.8.1 64bit http://people.salixos.org/djemos/razor-qt/ You can build it for your kde-4.5.5 by downloading the SLKBUILD and getopt.h.patch and run
I agree with most of the comments in this thread. Razor-qt may be worth watching but I certainly wouldn't build a distro with that as the default desktop. I also wonder if a qt based DE can ever be truly fast or lightweight.