You have three options:
-Install from source. Good luck
-Pickup the official redhat binaries from:
ftp://download.uk.kde.org/pub/kde/stable/3.1.1/RedHat/8.0/i386/
e.g.:
wget ftp://download.uk.kde.org/pub/kde/stable/3.1.1/RedHat/8.0/i386/*
rpm -Uvh *rpm
This way rpm determines the right sequense. But it takes a while.
And redhat crippled the kde code a little bit, but it worked for me.
-Or try this site http://kde-redhat.sourceforge.net/. I haven't tried this. But i think they haven't modified the code.