Have you tried getting the last SlackBuild scripts for KDE 3.5.x and
comparing them to the build scripts for KDE-4.2.4 in Slackware64?
Maybe start with:
diff -u ./slackware-12.2/source/kde/KDE.SlackBuild ./slackware64-current/source/kde/KDE.SlackBuild
so you'll get an idea of what building KDE is all about.
Have you looked at some of Woodsman's KDE rants? He really does not
want to use KDE4, though he wants to use Slackware-13.0. Perhaps
there are some hints there. Pay close attention to all of Alien Bob's
You can post some screenshots of your modified KDE-3.5.x