Thank You for posting, Herve. This is very valuable experience in case others hit the same problem with 32 vs. 64bit JDK compatibility.
The instructions on the Labs page (and our sample pre-packaged ecliplse zip) use Ecliplse 3.4.2. But in hindsight I think Ecliplse 3.5 is much easier to set up and configure for the Component Development Tool anyway. For example you can just use its Updater to add "Modeling" support and you are ready to install the Plug-in (no need to install GEF and EMF as separarate updates).
Please do post any feedback or feature ehancement that you think would be worthwhile.