The Lomboz 3.0rc2 release works perfectly together with Eclipse 3.0. You can download it here (lomboz.3rc2.zip).
Please make sure to download the accompanying Eclipse Modelling Framework (EMF) plug-in too (emf-sdo-runtime-I200406100948.zip)!
EMF by the way, seems to be an excellent tool
used to define and implement structured data models
see Using EMF for a nice introduction.
For configuration of the Lomboz plug-in, I suggest this tutorial once more