Get it in rpm form.
http://rpm.pbone.net
Search for libdvdcss and look for mandrake 10.1 or mandrake 10.x in the results.
Follow the link and download the file.
Open a terminal, cd to the dir where the libdvdcss rpm is, su to root and type
rpm -Uvh libdvdcss*
This should install it for you.