Hi,
I don't know if it helps but what I did was the following:
After compiling the entire KDE3.1
mv /opt/kde /opt/kde.orig
ln -s /opt/kde /root/kde3.1
chmod 755 /root/kde3.1
cp -R /opt/kde.orig/share/icons/ /opt/kde/share/icons/
cp -R /opt/kde.orig/share/wallpapper/ /opt/kde/share/wallpapper
I use Suse Linux and I wanted to have some of the custom Icons and wallpaper.
All users are now using the new kde3.1 as their default desktop. Excellent Desktop if I may say so myself.
Regards,
Ricardo