Hi,
I managed to get my C4580 (4500 series) connected to my router to work with 64 bit 5.3.
That printer needs at least hplip 2.8.10 which I found at http://rpm.pbone.net/index.php3/stat/4/idpl/12086038/com/hplip-2.8.10-0.1.el...
It was just a matter of following the manual install instructions for hplip here http://hplipopensource.com/hplip-web/install/manual/distros/redhatenterprise...
and then getting the necessary dependencies.
In the end it worked with (this is for the last line of step 3 in HP's instuctions)
rpm -Uvh ./hplip-2.8.10-0.1.el5.test.x86_64.rpm ./python-imaging-1.1.6-2.el5.rf.x86_64.rpm ./hpijs-2.8.10-0.1.el5.test.x86_64.rpm ./net-snmp-5.3.2.2-5.el5_3.1.x86_64.rpm ./net-snmp-libs-5.3.2.2-5.el5_3.1.x86_64.rpm ./lm_sensors-2.10.7-4.el5.x86_64.rpm
I'm happy with HP's Linux support!
Shawn