You don't ever install any libs through JWS. The problem lies with Apple. Because apple ships Java3D 1.3.1 with their OS, it always over-rides the new library that is set in JWS (through the classpath).
The only way to get around this is for Apple to not ship Java3D and or for Apple to go ahead and include Java3D 1.5 with their next updates. But your battle is with apple on this one, not Sun.
Therefore, if you test the following game under Mac OS X 10.5 for example, it will work:http://www.realsimulation3d.com/downctr.php?file=http://www.realsimulation3d.com/webstart/vu.jnlp
Can someone test if it works? I would like to add it into the FGF players' portal. I have the same "problem" with "Arabian Flights" that uses Java3D.