As far as I know, RedHat puts a lot of stuff in other directories than is standard for KDE. They also modify the sources heavily to cater for their... well.. ehrmm.. changes.. (don't want to start a flame war here :lol: ).
You will have to check out your system to see where RedHat put it's stuff, and change the Konstruct script accordingly (or give it the parameters to deal with the different location).
What has happened with you, in any case, is that your system has KDE already (in the RedHat flavor), and you built and installed KDE through Konstruct. Konstruct put it in the default location, most likely, but your configuration files for X (where it's told what window manager, etc. to use) are still pointing towards the RedHat KDE version.
