Dude you have a big project ahead of you... I never got to upgrading KDE on Redhat 9 when I had it. If KDE is too big to download, I would recommend you ask to download it at your school (i'm assuming you are still at school here) or when you have internet access. But I don't believe you could download only some of it though, because it's a fairly big thing
I'm running Gentoo
now and KDE upgrades are a breeze, but I wouldn't recommend it if you don't own a 24/7 connection. Anyway, how to upgrade KDE on redhat... I would try the RPM's provided by Redhat, but i do believe that the Redhat 9 RPM tree (the place the packages for your sistem are) is frozen in time and not updated, which brings us to your problem: you can't upgrade KDE because even if you did stumble upon an RPM you could not meet the dependencies (i'm not 100% here though). Users have been asked repeatedly to move to Fedora Core. I hear it is very stable, and would recommend the same action to you.
Cheers, and good luck.