CentOS - Nov 2007 - Linux driver for HP Laserjet 3500 printer - yum won't install

I'm trying to install the linux driver for an HP Colour Laserjet 3500 in
CentOS 5. I've installed the kde.repo (with appropriate priorities set
up), but when I try yum install pxljr-1.1-1.i386.rpm, yum says 'nothing
to do' - is this because the priority protection won't let it install
from the kde repo?
The alternative approach seems to be to use yum localinstall with the
downloaded package, but then I get the message that 'the package is not
signed'. So how do I resolve that please - the instructions regarding
'signing of packages' don't seem very clear to those of us who
weren't
'born and bred' on linux!

Thanks,
Andy