As step 1, I have resurrected KitchenSync - the KDE OpenSync frontend. This application allows for creating, configuring, and syncing OpenSync sync groups among any of the OpenSync plugins (check your distro for opensync-plugin-* or similar).
Basic use should be straightforward - add a sync group, add the members you want to sync between, configure if necessary, sync.
The underlying OpenSync 0.22 framework is showings its age a bit though, and does have some bugs, so if you see a problem in KitchenSync, first make sure that the syncing works with the command-line tool msynctool before reporting a bug in KitchenSync (which, for this version, you can do by directly contacting me here on this blog or via email). Msynctool will also show a bit more debugging output so if something is going wrong, definitely check there first.
I've made binary and source RPMs available for openSUSE 11.1 and newer on the OBS in KDE:Unstable:Playground, which I'll try and keep updated whenever I can.
The source tarball is also available thanks to the OBS. I'll see about getting some publicly accessible source repository soon.
Prerequisites are libopensync-devel, libkde4-devel, and kdepimlibs4-devel or whatever similar name your distro calls them. Compilation instructions are standard KDE SC 4 / cmake stuff.
mkdir build; cd build cmake .. make make install
The release is available on KDE-Apps.org.
In an entirely coincidental event, Quentin Denis has revived the KDE4 + OpenSync 0.40 version of KitchenSync on KDE SVN too. This does not overlap with his work; OpenSync 0.40 is not compatible with OpenSync 0.22. However, I'll be keeping track of his development and backporting any useful fixes (and lending any help I can).