How do I install only the KDE desktop (and not apps) on Unity?

My question is pretty simple. I have Ubuntu 12.04 with Unity and I want to login with KDE.

I have seen recommendations to:

1- run the three commands:
$ sudo add-apt-repository ppa:kubuntu-ppa/backports
$ sudo apt-get update
$ sudo apt-get install kubuntu-desktop

2- run just the command:
$ sudo apt-get install kubuntu-desktop

3- run the command:
$ sudo apt-get install kde-standard

4- run the command:
$ sudo apt-get install kde-full

5- run the command:
$ sudo apt-get install plasma-desktop

6- run the command:
$ sudo apt-get install kde-plasma-desktop

7- etc ...

This question is very related to this one, but the answer there is not clear enough to me. There seems to be quite a number of quasi-identical commands one could use to install the KDE desktop.

I just want the desktop, no KDE apps since I'll just use the ones I'm already using in Unity. Of course I also want the needed repositories added so the KDE desktop will be kept updated.

How would I go about doing that?

The command / package you want is :

sudo apt-get install kde-plasma-desktop

You can also search software centre for 'kde-plasma-desktop' and install it that way.

This package installs KDE desktop with minimal applications, and you can continue to use you ubuntu/gnome apps with it. I have used this with no problems, just select KDE from the login menu once it has been installed.

The KDE packages will be automatically updated through update manager once installed.

It's best to install the kubuntu-desktop package first and THEN remove any installed KDE apps you don't need. This way, you get the full desktop environment experience and can stay updated, while not keeping redundant programs installed.

Note that a lot of Unity/Gnome apps will not behave according to the KDE theme set as a KDE-native app would.