Yep. I've recovered RPM based systems using the chroot environment using a different distro's Live CD, which I just had to hand. I think it was glibc & ldd which I managed to screw up. Usually when ppl claim something is hard to do with rpm(8), it's because they couldn't understand the man page or lacked the stamina to find the right piece.
openSUSE supported installing both KDE3 & KDE4, thought it was best to experiment with KDE4 under a different username to avoid trouble going back to KDE 3.5, which the packaging without dependency solution also fails to address.