Just wanted to notify everybody here that I have succeeded in web starting J3D both under Linux and Windows.
The only issue I cannot resolve is how to let JWS detect if the target windows machine supports the OpenGL or Direct3D version of J3D. I am assuming it's impossible to do this, but if anybody knows a way?!
Furthermore, there is the legal issue of distributing (parts of) J3D.
Finally, is there a way to detect if J3D is already installed as a standard extension? Currently, the JWS application will download a copy of J3D regardless of the fact that it might already be installed.