These instructions assume that you already know how to build KDE stuff from source. It just provides a list of what you need to checkout and build, and how to run it.
You will need a working Nepomuk on your system (strigi indexer not required to be on, but Nepomuk must be enabled), with the virtuoso backend.
You will also need to install several cross-desktop Telepathy components. Packages of the following from your distribution should do fine.
The prerequisite for all the Telepathy stuff to build is the TelepathyQt4 library. The source code for this is available here. Your distribution may package it, in which case you need version >= 0.2.2. Be careful not to confuse it with the telepathy-qt library which used to be in kdesupport SVN. This is *completely* different and in no way compatible.
If you are building your own copy of TelepathyQt4, clone the git repository linked above, and use the usual autotools method to build and install it.
The next thing to get set up is the Telepathy Accounts KCM. This is the UI for account management.
Source code is here.
This can be compiled and installed by the usual KDE build procedure.
You will also want the plugins for this app, found in svn here.
This daemon integrates Telepathy with Nepomuk, which is required by the Contact List application. Code is in svn here
This application provides a traditional contact-list, similar to the one provided by Kopete. Code is in svn here