I am actually using Slackware 13.37 RC 4.6692, that will very likely become the final release of Slackware 13.37. Because I am lazy, I make use of the very comfortable slapt-get tool that enables an apt-get like package manager on Slackware Gnu/Linux.
If you want to install KDE 4.6.x (version 4.6.2 at this moment), follow the great tutorial and packages built by mr Eric Hameleers, also known as Alien.
After you installed (and enjoyed) KDE, you may desire to block future updates made using slapt-get, that will try to “upgrade” your KDE packages (and dependencies) with those on Slackware repository. It’s easy! Just open the file /etc/slapt-get/slapt-getrc and add the word alien at the end of the EXCLUDED list. So it would look like:
From now on, each package ending with “-*alien” will be excluded by upgrades made using slapt-get.