That's what I found, collected and provided in a cookbook format:
1) Download a fresh copy of Eclipse 3.4 / Ganymede. I've used the EE release, but the others should work, too.
2) Follow this cook book for the subversion part.
3) Install the Maven 2 plugin from this site: http://m2eclipse.sonatype.org/update/
4) Test it with a subversion based project, e.g. my favourite is CAS. m2eclipse is officially supported by that project. However, you have to activate the "Include Modules" property in the project to get rid of initial errors. I've reported this on the CAS mailing list.
