I've got slackware 12.1, and i'd like to install kde 4.1.1, I've been following http://techbase.kde.org/Getting_Star...d/KDE4/Generic but when i got to the part about qt4 the https server asked for a un and pw that idk. so i googled around for qt4 and found http://slackit.wordpress.com/category/qt4/, now it's giving me an error during the ./config that I don't have SQLite3, How to i get SQLite3? and why do I need it if I have MySql(which to my understanding comes with slackware and is currently installed). And if I do need it where do I get it? All I can find is that it comes with Tcl/tk(which of course I also already have).

This is quite a task.
If you just want to try it, get a live distribution that comes with kde4. The problem here is that you have to replace so much stuff that you create many potential problems. And KDE4 isn't exactly rock solid as it is.

Go to Slackware's website and select Get Slack. Select a mirror. From the mirror site, go to slackware-current/testing/packages/kde4/

From here read the README file. You may also want to run the two shell files from this location to clean up any conflicts.

My mistake - this would be for 4.1.0

I have not tried it yet, but there is a build script that if edited might help.
Again, from your favorite mirror - slackware-current/testing/source/kde4/kde/KDE.SlackBuild

If you only need sqlite for Slackware, check out slackware-current/testing/packages/kde4/deps/sqlite-3.6.1-i486-1.tgz

by replacing stuff do you mean i won't be able to go back to kde3? I'd like to have the option like in Kubuntu where I can install kde4, and set the session to kde3 or 4(or xfce or w/e).

You'll have duplicates of lots of stuff, including the QT library. I don't know how ubuntu does it.