The packages you linked are incomplete and do not provide a full 3.5.10 package suite.
A few people participating in this forum have built and installed 3.5.10 in 13.1. Building new packages requires patience and a bunch of patches to compile with newer versions of gcc, libpng, etc.
I'm waiting for Current to go official before I start testing 3.5 there, but mostly because I'm busy with other things right now.
Easier solution: A few people have installed on 13.1 the 3.5.10 packages made for Slackware 12.2. No recompiling required. That strategy requires removing the KDE 4 packages to avoid conflicts with files of the same name. You can leave qt4 installed. Remember to install dbus-qt3, qca, qca-tls, and qt-3.3.8b. You should recompile poppler with qt3 support. I think starting with 13.1, poppler is no longer built on the stock Slackware with qt3 support.
More info: KDE 3.5.x for Slackware