If you want run the xfce4-4.4RC2-installer.run from os-cillation you need a large amount of requirements on your system, especially if you start with a new and small debian system. The following requirements you can get with apt-get install “filename”
If you have done all this system requirements, you can go on with the installation through the os-cillation installer. Atfirst you must download the “xfce4-4.4RC2-installer.run”.
The next steps to do are accurately described at the installation manual.
Have fun with xfce !