Vamos atualizar o 
KDE 5_15.10 no 
Slackware, que é composto pelo KDE Frameworks 5.15.0, Plasma 5.4.2 e aplicações para o KDE "Applications" 15.08.2.
Atualizar do KDE 4.2 para o atual 5.15.10 (hoje!) deveria ser muito simples.
KDE-5_15.10 deve ser instalado apenas em uma instalação atualizada current e ela irá substituir qualquer versão do KDE 4 que você tenha instalado!
E lá vamos nós.... 
O que temos de novo nesse update?
-   Two updated "deps" packages: qca-qt5 and wayland.
-   A completely new subset of "deps" packages, contained in their own "telepathy" subdirectory, is paving the way for KDE Telepathy (see below): libotr, libnice, farstream, libaccounts-glib, libaccounts-qt5,  signon, signon-plugin-oauth2, signon-ui, libsignon-glib,  telepathy-glib, telepathy-farstream, telepathy-haze, telepathy-gabble, telepathy-qt5, telepathy-logger, telepathy-logger-qt5, telepathy-mission-control and telepathy-accounts-signon.
-   Frameworks 5.15.0 is an enhancement release, no new Framework was added. See  https://www.kde.org/announcements/kde-frameworks-5.15.0.php
-   Plasma 5.4.2 is a bugfix release, you can read the details in  https://www.kde.org/announcements/plasma-5.4.2.php.  Worth mentioning is that I have finally enabled the 'plasma-mediacenter' package.
-   In plasma-extra you will find a rebuilt sddm-qt5 package which fixes the  broken progress bar on startup of the Plasma Desktop session. Also you will  find a new package 'xembed-sni-proxy' which docks into the Plasma 5 system tray and provided a legacy XEmbed tray for those applications that need it.  It is therefore no longer necessary to use a program like trayer-srg or  stalonetray to make these XEmbed tray-icons visible.
-   Applications 15.08.2 is a bugfix release as well. But for my Slackware package set, the important change is that I have added all the KDE Telepathy packages that previously stayed un-built. You'll find a new systray icon  waiting for you to configure your IM accounts.  Only the voice & video GUI is still missing, the KDE Telepathy developers are still looking for someone knowledgeable to port the old KDE 4 version to Frameworks 5.
Outros pontos interessantes que não foram mudadas desde versões anteriores:
-   ConsoleKit2 replaces Slackware's ConsoleKit. Now we have something again which is properly maintained and well on its way to implementing the necessary parts of the systemd-logind API (so that we can ignore systemd).
-   kde/kde4-extragear packages should be taken from slackware-current (calligra, k3b, kaudiocreator, kplayer, kwebkitpart, oxygen-gtk2, kdevplatform,  kdevelop-pg-qt, kdevelop, kdev-python, kdevelop-php, kdevelop-php-docs,   skanlite, kio-mtp, libktorrent, ktorrent, partitionmanager)
-   Note that I did not compile KDEnlive which ships with Applications. It needs a lot of attention before I can build this (ffmpeg amd more is required).
-   katepart4 was added so that kdevelop works again
-   konsolepart4 was added to be able to use an embedded konsole in dolphin
-   kdeconnect4 was added; this stripped-down version of the KDE4 based  kdeconnect-kde allows you to access your Android device with the (also still KDE4 based) Dolphin filemanager
-   akonadi4 and kdepimlibs4 were added to support KDE 4 applications that call  PIM functionality.
-   sddm-theme-breeze was removed, the theme is now part of plasma-workspace
-   Lots of packages in the 'deps' department which are completely new to Slackware. Since KDE 5 is built on Qt5 (KDE 4 had Qt4 as its base) you'll find many Qt5 related packages. Also, in order for Qt4 and GTK based applications to dock into the Plasma 5 system tray, more dependencies were needed. So, apart from updates to regular Slackware packages and the aforementioned new telepathy support packages, these are the new ones: OpenAL, PyQT5, cfitsio, json-glib, libappindicator, libdbusmenu-gtk,  libdbusmenu-qt5, libindicator, lmdb, polkit-qt5-1, qca-qt5, qt-gstreamer, qt5, sni-qt, wayland and xapian-core.
-   Note for users of multilib Slackware64 and also using Skype: you will have to  grab the 32-bit version of sni-qt and run 'convertpkg-compat32' on it, or else Skype won't be able to dock its icon in the systray.
-   A bit sneakily, I built phonon-vlc for you.  You will also need a VLC package to be able to use this package though.
-   Several source tarballs in Plasma 5.4.x have not been compiled to Slackware  packages: libbluedevil and bluedevil (they need BlueZ 5 which is not part of  Slackware), muon (a debian/ubuntu package manager), libkface (needs opencv  which I was not willing to add as a dependency), user-manager and kwallet-pam  (need PAM), plasma-pa (needs pulseaudio).
-   One dependency which you'll probably find curious, is wayland. It is required  in order to *compile* KWin's X11 driver, but for using KWin inside a  X session it is not needed at *runtime*.
-   Graphical login: KDM has been replaced with SDDM. Slackware-current supports  it already.  Select "Plasma" from the SDDM session dropdown.  Alternatively, if you prefer good old runlevel 3, you can type (at your own  user account's command prompt):
 
 xwmconfig
 
 ... and select "xinitrc.plasma" as your default window manager for X.  Then run:
 
 startx
NOTA: também explicaremos abaixo em mais detalhes, atualizar para o KDE 5 não é uma coisa trivial. Você terá que remover todos os pacotes antigos do KDE manualmente. Se você não tem o KDE instalado até agora (acho difícil! mas...) você terá que instalar alguns pacotes do KDE manualmente.
Se você decidir instalar esse pacotes na versão mais atual do Slackware current e excluir todos os pacotes no série de pacotes 'KDE' durante a instalação, você irá perder alguns pacotes adicionais importantes, alguns desses pacotes são essenciais para o bom funcionamento do KDE!
Se você excluir a série 'KDE' do seu Slackware current completamente então você terá que instalar os seguintes pacotes do current pelo menos:
E opcionalmente instalar estes pacotes do current também:
-  amarok
-  calligra
-  k3b
-  kaudiocreator
-  kplayer
-  kwebkitpart
-  kdevplatform
-  kdevelop-pg-qt
-  kdevelop
-  kdev-python
-  kdevelop-php
-  kdevelop-php-docs
-  kio-mtp
-  ktorrent
-  oxygen-gtk2
-  partitionmanager
-  skanlite
Compilando isso tudo do fonte
Fontes e scripts estão separados nos pacotes do 'ktwon' no repositório  do alien. Se você quer os fontes do KDE 5 rode o seguinte comando para baixá-los. 
# rsync -av rsync://alien.slackbook.org/alien/ktown/source/5 .
Existem várias dependências para o KDE 5 que você terá que compilar e instalar antes de tentar compilar o KDE 5. Compilando e instalando essas dependências no slackware-current é simples basta dar o comando abaixo:
# cd 5/deps
# ./updates.SlackBuild
# cd -
Fique preparado para esperar bastante tempo uma vez que isso irá recompilar o Qt4 e o Qt5 e mais uma pancada de outros pacotes! Os pacotes serão salvos dentro da pasta /tmp.
Então pra você compilar os pacotes do KDE no seu computador rode o seguinte comando:
# cd 5/kde
# ./KDE.SlackBuild
Aguarde um longo tempo e depois você irá ver os pacotes na pasta in /tmp/kde-build.
Note que estes pacotes já foram instalados pelo KDE.Slackbuild!
Mas se você queria apenas criar os pacotes então aí estão eles. E você não precisa mais seguir esse tutorial. Caso queira realmente instalar (que é o objetivo desse post...), então vamos colocar a mão na massa!