I am interested in compiling KDE SC on a stock ubuntu-server distribution in under 7 days, and then updating the documentation so that a new contributor to KDE can do this in under 6 days. I think the huge up-front commitment to build from trunk is a barrier to entry for new contributors.
Here is a list of documentation that I am consulting and working on. They are listed in order from http://kde.org/community/getinvolved/, a place where new contributors can start, and is hierarchal based on hyper links. Action that is required is also included on this list. Ultimately, this should result in a runnable system.
Kernel panic during git update on qt-copy
I also read that you wanted to know how long the build process takes for new comers. In that regard, I had a very hard and long time at first understanding the process of building trunk besides my stable KDE. I tried building it several times, but every time it gave some compilation errors in different pieces of codes. This was may be because of wrong bashrc that I used for settings the env variables for KDE_SRC and KDE_BUILD.
But after I got that clear (a friend helped me through), the cmakekde on kdesupport+kdelibs+phonon+kdebase took about an hour and a half, excluding the source-code download time (it took really long due to my slow internet connection).
Glad I could help! Considering the ENTIRE time, it took me about a month (I know its too long but I gave up every time it gave errors, and did not try again till a week or so) to setup KDE from trunk. And of course, I don't mind my response being put on the wiki if it helps. Actually, I just posted a small and simple walkthrough on my blog for building KDE from trunk beside the stable distro-provided KDE. Take a look, if it helps either, http://31shebang.wordpress.com/2010/09/23/kde-from-the-trunk/