eclipse web tools
Lomboz contribution to the Eclipse Web Tools Platform Project is also now live. Here is the link. Scroll down to the end of the page and see ObjectWeb getting started guide.
Note that after extracting the zip file you got from eclipse.org to the same location as used above, it gives you a lomboz.zip file which must be extracted to your eclipse home directory. Thsi directory is the directory that is directory above the plugin folder. The lomboz tutorial is here.
XMI Toolkit is available as Eclipse Modeling Framework, which is part of the Eclipse open-source project.