After I deleted and unpacked Eclipse + EMF + MTJ runtime itself again, I
was able to make it work.
I did not install any Nokia stuff such as the S60 SDK or CONN.ZIP. Not
sure yet wether I will need that, but it looks as if even without it, i.e.
using the above together with the WTK 2.5 from Sun I can develop mobile
apps and test them on the emulator which comes with the WTK. I might need
the Nokia stuff when I want to deploy my app to a real phone probably.
Might it be that configuration information goes into the plugin directory
under $ECLIPSE_HOME/plugins/org.eclipse.mtj.xxx rather than
$WORKSPACE/.metadata/.plugins/.org.eclipse.mtj.xxx? Shall I file a bug?