Well, thanks to Harold (apachelogger) our resident packaging savant, we have the ability to test drive KDE 4.2 trunk daily. Remember, this is trunk we are dealing with and many things break, and possibly break quite often and maybe for extended periods of time. For this reason, you should never install this on your production machine.
I decided to give this a test drive, and figured the best way to do so was via a VM. So, I installed Virtualbox first and set it up. I won't go over all the details here, as there are a wide variety of docs available for setting up virtual box (aka google for it).
Once I had a VM drive all setup and installed with the latest Intrepid, added the KDE Nightly Neon repository (the PPA for KDE Nightly) to a new sources.list.d/neon.list file. The PPA is enabled by adding this entry:
deb http://ppa.launchpad.net/project-neon/ubuntu intrepid main
The next thing you need is to update your repositories package info. Either using your favorite package manager, and hit their update option, or from the command line execute the following:
sudo apt-get update
Now, you should have an updated package list which contains the Neon packages.
Next, using your package manager, locate the kde-nightly package and select/mark it for installation and apply it or execute the following from the command line:
sudo apt-get install kde-nightly
This will install the required files and setup a new kdm xsession for KDE Nightly (Neon). Once you logout and end up back to KDM, you can choose this new session (rather than the default KDE session).
Reference post can be found here.
Many thanks to apachelogger for this.